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| author | Anas Nashif <anas.nashif@intel.com> | 2012-10-30 12:57:26 -0700 |
|---|---|---|
| committer | Anas Nashif <anas.nashif@intel.com> | 2012-10-30 12:57:26 -0700 |
| commit | 1a78a62555be32868418fe52f8e330c9d0f95d5a (patch) | |
| tree | d3765a80e7d3b9640ec2e930743630cd6b9fce2b /doc/html/typeof | |
| download | boost-1a78a62555be32868418fe52f8e330c9d0f95d5a.tar.gz boost-1a78a62555be32868418fe52f8e330c9d0f95d5a.tar.bz2 boost-1a78a62555be32868418fe52f8e330c9d0f95d5a.zip | |
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diff --git a/doc/html/typeof/ackn.html b/doc/html/typeof/ackn.html new file mode 100755 index 0000000000..cb76ca9f94 --- /dev/null +++ b/doc/html/typeof/ackn.html @@ -0,0 +1,90 @@ +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> +<title>Acknowledgements</title> +<link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> +<meta name="generator" content="DocBook XSL Stylesheets V1.76.1"> +<link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> +<link rel="up" href="../typeof.html" title="Chapter 31. Boost.Typeof"> +<link rel="prev" href="cont.html" title="Contributed By:"> +<link rel="next" href="../boost_units.html" title="Chapter 32. Boost.Units 1.1.0"> +</head> +<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> +<table cellpadding="2" width="100%"><tr> +<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td> +<td align="center"><a href="../../../index.html">Home</a></td> +<td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td> +<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> +<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> +<td align="center"><a href="../../../more/index.htm">More</a></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="cont.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../typeof.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../boost_units.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +<div class="section"> +<div class="titlepage"><div><div><h2 class="title" style="clear: both"> +<a name="typeof.ackn"></a>Acknowledgements</h2></div></div></div> +<p> + The idea of representing a type as multiple compile-time integers, and passing + these integers across function boundaries using sizeof(), was taken from Steve + Dewhurst's article "A Bitwise typeof Operator", CUJ 2002. This article + can also be viewed online, at <a href="http://www.semantics.org/localarchive.html" target="_top">http://www.semantics.org/localarchive.html</a>. + </p> +<p> + Special thank you to Paul Mensonides, Vesa Karvonen, and Aleksey Gurtovoy for + the Boost Preprocessor Library and MPL. Without these two libraries, this typeof + implementation would not exist. + </p> +<p> + The following people provided support, gave valuable comments, or in any other + way contributed to the library development (in alphabetical order): + </p> +<div class="itemizedlist"><ul class="itemizedlist" type="disc"> +<li class="listitem"> + David Abrahams + </li> +<li class="listitem"> + Andrey Beliakov + </li> +<li class="listitem"> + Joel de Guzman + </li> +<li class="listitem"> + Daniel James + </li> +<li class="listitem"> + Vesa Karvonen + </li> +<li class="listitem"> + Andy Little + </li> +<li class="listitem"> + Paul Mensonides + </li> +<li class="listitem"> + Alexander Nasonov + </li> +<li class="listitem"> + Tobias Schwinger + </li> +<li class="listitem"> + Martin Wille + </li> +</ul></div> +</div> +<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> +<td align="left"></td> +<td align="right"><div class="copyright-footer">Copyright © 2004, 2005 Arkadiy Vertleyb, Peder Holt<p> + Distributed under the Boost Software License, Version 1.0. (See accompanying + file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top"> + http://www.boost.org/LICENSE_1_0.txt </a>) + </p> +</div></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="cont.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../typeof.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../boost_units.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +</body> +</html> diff --git a/doc/html/typeof/cont.html b/doc/html/typeof/cont.html new file mode 100755 index 0000000000..c916beaf6f --- /dev/null +++ b/doc/html/typeof/cont.html @@ -0,0 +1,51 @@ +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> +<title>Contributed By:</title> +<link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> +<meta name="generator" content="DocBook XSL Stylesheets V1.76.1"> +<link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> +<link rel="up" href="../typeof.html" title="Chapter 31. Boost.Typeof"> +<link rel="prev" href="other.html" title="Other considerations and tips"> +<link rel="next" href="ackn.html" title="Acknowledgements"> +</head> +<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> +<table cellpadding="2" width="100%"><tr> +<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td> +<td align="center"><a href="../../../index.html">Home</a></td> +<td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td> +<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> +<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> +<td align="center"><a href="../../../more/index.htm">More</a></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="other.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../typeof.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="ackn.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +<div class="section"> +<div class="titlepage"><div><div><h2 class="title" style="clear: both"> +<a name="typeof.cont"></a>Contributed By:</h2></div></div></div> +<div class="itemizedlist"><ul class="itemizedlist" type="disc"> +<li class="listitem"> + Compliant compilers -- Arkadiy Vertleyb, Peder Holt + </li> +<li class="listitem"> + MSVC 6.5, 7.0, 7.1 -- Igor Chesnokov, Peder Holt + </li> +</ul></div> +</div> +<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> +<td align="left"></td> +<td align="right"><div class="copyright-footer">Copyright © 2004, 2005 Arkadiy Vertleyb, Peder Holt<p> + Distributed under the Boost Software License, Version 1.0. (See accompanying + file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top"> + http://www.boost.org/LICENSE_1_0.txt </a>) + </p> +</div></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="other.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../typeof.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="ackn.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +</body> +</html> diff --git a/doc/html/typeof/other.html b/doc/html/typeof/other.html new file mode 100755 index 0000000000..10f26e1b71 --- /dev/null +++ b/doc/html/typeof/other.html @@ -0,0 +1,326 @@ +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> +<title>Other considerations and tips</title> +<link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> +<meta name="generator" content="DocBook XSL Stylesheets V1.76.1"> +<link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> +<link rel="up" href="../typeof.html" title="Chapter 31. Boost.Typeof"> +<link rel="prev" href="refe.html" title="Reference"> +<link rel="next" href="cont.html" title="Contributed By:"> +</head> +<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> +<table cellpadding="2" width="100%"><tr> +<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td> +<td align="center"><a href="../../../index.html">Home</a></td> +<td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td> +<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> +<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> +<td align="center"><a href="../../../more/index.htm">More</a></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="refe.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../typeof.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="cont.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +<div class="section"> +<div class="titlepage"><div><div><h2 class="title" style="clear: both"> +<a name="typeof.other"></a>Other considerations and tips</h2></div></div></div> +<div class="toc"><dl> +<dt><span class="section"><a href="other.html#typeof.natem">Native typeof support and emulation</a></span></dt> +<dt><span class="section"><a href="other.html#typeof.parties">The three participating parties</a></span></dt> +<dt><span class="section"><a href="other.html#typeof.features">Supported features</a></span></dt> +<dt><span class="section"><a href="other.html#typeof.what">What needs to be registered?</a></span></dt> +<dt><span class="section"><a href="other.html#typeof.limi">Limitations</a></span></dt> +</dl></div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.natem"></a>Native typeof support and emulation</h3></div></div></div> +<p> + Many compilers support typeof already, most noticeable GCC and Metrowerks. + </p> +<p> + Igor Chesnokov discovered a method that allows to implement <code class="computeroutput"><span class="identifier">typeof</span></code> on the VC series of compilers. It + uses a bug in the Microsoft compiler that allows a nested class of base to + be defined in a class derived from base: + </p> +<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">int</span> <span class="identifier">ID</span><span class="special">></span> <span class="keyword">struct</span> <span class="identifier">typeof_access</span> +<span class="special">{</span> + <span class="keyword">struct</span> <span class="identifier">id2type</span><span class="special">;</span> <span class="comment">//not defined</span> +<span class="special">};</span> + +<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">int</span> <span class="identifier">ID</span><span class="special">></span> <span class="keyword">struct</span> <span class="identifier">typeof_register</span> <span class="special">:</span> <span class="identifier">typeof_access</span> +<span class="special">{</span> + <span class="comment">// define base's nested class here</span> + <span class="keyword">struct</span> <span class="identifier">typeof_access</span><span class="special">::</span><span class="identifier">id2type</span> + <span class="special">{</span> + <span class="keyword">typedef</span> <span class="identifier">T</span> <span class="identifier">type</span><span class="special">;</span> + <span class="special">};</span> +<span class="special">};</span> + +<span class="comment">//Type registration function </span> +<span class="identifier">typeof_register</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">compile</span><span class="special">-</span><span class="identifier">time</span><span class="special">-</span><span class="identifier">constant</span><span class="special">></span> <span class="identifier">register_type</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span><span class="special">&);</span> + +<span class="comment">//Actually register type by instantiating typeof_register for the correct type</span> +<span class="keyword">sizeof</span><span class="special">(</span><span class="identifier">register_type</span><span class="special">(</span><span class="identifier">some</span><span class="special">-</span><span class="identifier">type</span><span class="special">));</span> + +<span class="comment">//Use the base class to access the type.</span> +<span class="keyword">typedef</span> <span class="identifier">typeof_access</span><span class="special">::</span><span class="identifier">id2type</span><span class="special">::</span><span class="identifier">type</span> <span class="identifier">type</span><span class="special">;</span> +</pre> +<p> + Peder Holt adapted this method to VC7.0, where the nested class is a template + class that is specialized in the derived class. + </p> +<p> + In VC8.0, it seemed that all the bug-featire had been fixed, but Steven Watanabe + managed to implement a more rigorous version of the VC7.0 fix that enables + 'typeof' to be supported 'natively' here as well. + </p> +<p> + For many other compilers neither native <code class="computeroutput"><span class="identifier">typeof</span></code> + support nor the trick described above is an option. For such compilers the + emulation method is the only way of implementing <code class="computeroutput"><span class="identifier">typeof</span></code>. + </p> +<p> + According to a rough estimate, at the time of this writing the introduction + of the <code class="computeroutput"><span class="identifier">typeof</span></code>, <code class="computeroutput"><span class="keyword">auto</span></code>, etc., into the C++ standard may not + happen soon. Even after it's done, some time still has to pass before most + compilers implement this feature. But even after that, there always are legacy + compilers to support (for example now, in 2005, many people are still using + VC6, long after VC7.x, and even VC8.0 beta became available). + </p> +<p> + Considering extreme usefulness of the feature right now, it seems to make + sense to implement it at the library level. + </p> +<p> + The emulation mode seems to be important even if a better option is present + on some particular compiler. If a library author wants to develop portable + code using <code class="computeroutput"><span class="identifier">typeof</span></code>, she needs + to use emulation mode and register her types and templates. Those users who + have a better option can still take advantage of it, since the registration + macros are defined as no-op on such compilers, while the users for whom emulation + is the only option will use it. + </p> +<p> + The other consideration applies to the users of VC7.1. Even though the more + convenient <code class="computeroutput"><span class="identifier">typeof</span></code> trick is + available, the possibility of upgrade to VC8, where emulation remains the + only option, should be considered. + </p> +<p> + The emulation mode can be forced on the compilers that don't use it by default + by defining the <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_COMPLIANT</span></code> + symbol: + </p> +<pre class="programlisting"><span class="identifier">g</span><span class="special">++</span> <span class="special">-</span><span class="identifier">D</span> <span class="identifier">BOOST_TYPEOF_COMPLIANT</span> <span class="special">-</span><span class="identifier">I</span> <span class="special">\</span><span class="identifier">boost</span><span class="special">\</span><span class="identifier">boost_1_32_0</span> <span class="identifier">main</span><span class="special">.</span><span class="identifier">cpp</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.parties"></a>The three participating parties</h3></div></div></div> +<p> + The Lambda example from the Motivation section requires the following registration: + </p> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="identifier">BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP</span><span class="special">()</span> + +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">tuples</span><span class="special">::</span><span class="identifier">tuple</span><span class="special">,</span> <span class="number">2</span><span class="special">);</span> +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lambda</span><span class="special">::</span><span class="identifier">lambda_functor</span><span class="special">,</span> <span class="number">1</span><span class="special">);</span> +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lambda</span><span class="special">::</span><span class="identifier">lambda_functor_base</span><span class="special">,</span> <span class="number">2</span><span class="special">);</span> +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lambda</span><span class="special">::</span><span class="identifier">relational_action</span><span class="special">,</span> <span class="number">1</span><span class="special">);</span> +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lambda</span><span class="special">::</span><span class="identifier">logical_action</span><span class="special">,</span> <span class="number">1</span><span class="special">);</span> +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lambda</span><span class="special">::</span><span class="identifier">other_action</span><span class="special">,</span> <span class="number">1</span><span class="special">);</span> +<span class="identifier">BOOST_TYPEOF_REGISTER_TYPE</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lambda</span><span class="special">::</span><span class="identifier">greater_action</span><span class="special">);</span> +<span class="identifier">BOOST_TYPEOF_REGISTER_TYPE</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lambda</span><span class="special">::</span><span class="identifier">less_action</span><span class="special">);</span> +<span class="identifier">BOOST_TYPEOF_REGISTER_TYPE</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lambda</span><span class="special">::</span><span class="identifier">and_action</span><span class="special">);</span> +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lambda</span><span class="special">::</span><span class="identifier">placeholder</span><span class="special">,</span> <span class="special">(</span><span class="keyword">int</span><span class="special">));</span> +</pre> +<p> + It may seem that the price for the ability to discover the expression's type + is too high: rather large amount of registration is required. However note + that all of the above registration is done only once, and after that, any + combination of the registered types and templates would be handled. Moreover, + this registration is typically done not by the end-user, but rather by a + layer on top of some library (in this example -- Boost.Lambda). + </p> +<p> + When thinking about this, it's helpful to consider three parties: the typeof + facility, the library (probably built on expression templates principle), + and the end-user. The typeof facility is responsible for registering fundamental + types. The library can register its own types and templates. + </p> +<p> + In the best-case scenario, if the expressions always consist of only fundamental + types and library-defined types and templates, a library author can achieve + the impression that the <code class="computeroutput"><span class="identifier">typeof</span></code> + is natively supported for her library. On the other hand, the more often + expressions contain user-defined types, the more responsibility is put on + the end-user, and therefore the less attractive this approach becomes. + </p> +<p> + Thus, the ratio of user-defined types in the expressions should be the main + factor to consider when deciding whether or not to apply the typeof facility. + </p> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.features"></a>Supported features</h3></div></div></div> +<p> + The Typeof library pre-registers fundamental types. For these types, and + for any other types/templates registered by the user library or end-user, + any combination of the following is supported: + </p> +<div class="itemizedlist"><ul class="itemizedlist" type="disc"> +<li class="listitem"> + Pointers; + </li> +<li class="listitem"> + References (except top-level); + </li> +<li class="listitem"> + Consts (except top-level); + </li> +<li class="listitem"> + Volatiles (except top-level); + </li> +<li class="listitem"> + Arrays; + </li> +<li class="listitem"> + Functions, function pointers, and references; + </li> +<li class="listitem"> + Pointers to member functions; + </li> +<li class="listitem"> + Pointers to data members. + </li> +</ul></div> +<p> + For example the following type: + </p> +<pre class="programlisting"><span class="keyword">int</span><span class="special">&</span> <span class="special">(*)(</span><span class="keyword">const</span> <span class="keyword">volatile</span> <span class="keyword">char</span><span class="special">*,</span> <span class="keyword">double</span><span class="special">[</span><span class="number">5</span><span class="special">],</span> <span class="keyword">void</span><span class="special">(*)(</span><span class="keyword">short</span><span class="special">))</span> +</pre> +<p> + is supported right away, and something like: + </p> +<pre class="programlisting"><span class="keyword">void</span> <span class="special">(</span><span class="identifier">MyClass</span><span class="special">::*)(</span><span class="keyword">int</span> <span class="identifier">MyClass</span><span class="special">::*,</span> <span class="identifier">MyClass</span><span class="special">[</span><span class="number">10</span><span class="special">])</span> <span class="keyword">const</span> +</pre> +<p> + is supported provided <code class="computeroutput"><span class="identifier">MyClass</span></code> + is registered. + </p> +<p> + The Typeof Library also provides registration files for most STL classes/templates. + These files are located in the std subdirectory, and named after corresponding + STL headers. These files are not included by the typeof system and have to + be explicitly included by the user, as needed: + </p> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">typeof</span><span class="special">/</span><span class="identifier">std</span><span class="special">/</span><span class="identifier">functional</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> +<span class="identifier">BOOST_AUTO</span><span class="special">(</span><span class="identifier">fun</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">bind2nd</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">less</span><span class="special"><</span><span class="keyword">int</span><span class="special">>(),</span> <span class="number">21</span><span class="special">));</span> <span class="comment">//create named function object for future use.</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.what"></a>What needs to be registered?</h3></div></div></div> +<p> + It is possible to take advantage of the compiler when registering types for + the Typeof Library. Even though there is currently no direct support for + typeof in the language, the compiler is aware of what the type of an expression + is, and gives an error if it encounters an expression that has not been handled + correctly. In the <code class="computeroutput"><span class="identifier">typeof</span></code> + context, this error message will contain clues to what types needs to be + registered with the Typeof Library in order for <code class="computeroutput"><span class="identifier">BOOST_TYPEOF</span></code> + to work. + </p> +<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">X</span> <span class="special">{};</span> + +<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">A</span><span class="special">,</span><span class="keyword">bool</span> <span class="identifier">B</span><span class="special">></span> +<span class="keyword">struct</span> <span class="identifier">Y</span> <span class="special">{};</span> + +<span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">X</span><span class="special">,</span><span class="identifier">Y</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span><span class="keyword">true</span><span class="special">></span> <span class="special">></span> <span class="identifier">a</span><span class="special">;</span> + +<span class="identifier">BOOST_AUTO</span><span class="special">(</span><span class="identifier">a</span><span class="special">,</span><span class="identifier">b</span><span class="special">);</span> +</pre> +<p> + We get the following error message from VC7.1 + </p> +<pre class="programlisting">error C2504: 'boost::type_of::'anonymous-namespace'::encode_type_impl<V,Type_Not_Registered_With_Typeof_System>' : base + class undefined + with + [ + V=boost::type_of::'anonymous-namespace'::encode_type_impl<boost::mpl::vector0<boost::mpl::na>,std::pair<X,Y<int,true>>>::V0, + Type_Not_Registered_With_Typeof_System=X + ] +</pre> +<p> + Inspecting this error message, we see that the compiler complains about + <code class="computeroutput"><span class="identifier">X</span></code> + </p> +<pre class="programlisting"><span class="identifier">BOOST_TYPEOF_REGISTER_TYPE</span><span class="special">(</span><span class="identifier">X</span><span class="special">);</span> <span class="comment">//register X with the typeof system</span> +</pre> +<p> + Recompiling, we get a new error message from VC7.1 + </p> +<pre class="programlisting">error C2504: 'boost::type_of::'anonymous-namespace'::encode_type_impl<V,Type_Not_Registered_With_Typeof_System>' : base + class undefined + with + [ + V=boost::type_of::'anonymous-namespace'::encode_type_impl<boost::mpl::vector0<boost::mpl::na>,std::pair<X,Y<int,true>>>::V1, + Type_Not_Registered_With_Typeof_System=Y<int,true> + ] +</pre> +<p> + Inspecting this error message, we see that the compiler complains about + <code class="computeroutput"><span class="identifier">Y</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span><span class="keyword">true</span><span class="special">></span></code>. Since <code class="computeroutput"><span class="identifier">Y</span></code> + is a template, and contains integral constants, we need to take more care + when registering: + </p> +<pre class="programlisting"><span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">Y</span><span class="special">,(</span><span class="keyword">typename</span><span class="special">)(</span><span class="keyword">bool</span><span class="special">));</span> <span class="comment">//register template class Y</span> +</pre> +<p> + It is a good idea to look up the exact definition of <code class="computeroutput"><span class="identifier">Y</span></code> + when it contains integral constants. For simple template classes containing + only typenames, you can rely solely on the compiler error. + </p> +<p> + The above code now compiles. + </p> +<p> + This technique can be used to get an overview of which types needs to be + registered for a given project in order to support <code class="computeroutput"><span class="identifier">typeof</span></code>. + </p> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.limi"></a>Limitations</h3></div></div></div> +<p> + Nested template template parameters are not supported, like: + </p> +<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span><span class="special">></span> <span class="keyword">class</span><span class="special">></span> <span class="keyword">class</span> <span class="identifier">Tpl</span><span class="special">></span> +<span class="keyword">class</span> <span class="identifier">A</span><span class="special">;</span> <span class="comment">// can't register!</span> +</pre> +<p> + Classes and templates nested inside other templates also can't be registered + because of the issue of nondeduced context. This limitation is most noticeable + with regards to standard iterators in Dinkumware STL, which are implemented + as nested classes. Instead, instantiations can be registered: + </p> +<pre class="programlisting"><span class="identifier">BOOST_TYPEOF_REGISTER_TYPE</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special"><</span><span class="keyword">int</span><span class="special">>::</span><span class="identifier">const_iterator</span><span class="special">)</span> +</pre> +</div> +</div> +<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> +<td align="left"></td> +<td align="right"><div class="copyright-footer">Copyright © 2004, 2005 Arkadiy Vertleyb, Peder Holt<p> + Distributed under the Boost Software License, Version 1.0. (See accompanying + file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top"> + http://www.boost.org/LICENSE_1_0.txt </a>) + </p> +</div></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="refe.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../typeof.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="cont.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +</body> +</html> diff --git a/doc/html/typeof/refe.html b/doc/html/typeof/refe.html new file mode 100755 index 0000000000..756317fbdd --- /dev/null +++ b/doc/html/typeof/refe.html @@ -0,0 +1,585 @@ +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> +<title>Reference</title> +<link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> +<meta name="generator" content="DocBook XSL Stylesheets V1.76.1"> +<link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> +<link rel="up" href="../typeof.html" title="Chapter 31. Boost.Typeof"> +<link rel="prev" href="tuto.html" title="Tutorial"> +<link rel="next" href="other.html" title="Other considerations and tips"> +</head> +<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> +<table cellpadding="2" width="100%"><tr> +<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td> +<td align="center"><a href="../../../index.html">Home</a></td> +<td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td> +<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> +<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> +<td align="center"><a href="../../../more/index.htm">More</a></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="tuto.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../typeof.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="other.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +<div class="section"> +<div class="titlepage"><div><div><h2 class="title" style="clear: both"> +<a name="typeof.refe"></a>Reference</h2></div></div></div> +<div class="toc"><dl> +<dt><span class="section"><a href="refe.html#typeof.auto">AUTO, AUTO_TPL</a></span></dt> +<dt><span class="section"><a href="refe.html#typeof.compl">COMPLIANT</a></span></dt> +<dt><span class="section"><a href="refe.html#typeof.incr">INCREMENT_REGISTRATION_GROUP</a></span></dt> +<dt><span class="section"><a href="refe.html#typeof.inte">INTEGRAL</a></span></dt> +<dt><span class="section"><a href="refe.html#typeof.limit_func">LIMIT_FUNCTION_ARITY</a></span></dt> +<dt><span class="section"><a href="refe.html#typeof.messages">MESSAGES</a></span></dt> +<dt><span class="section"><a href="refe.html#typeof.limit_size">LIMIT_SIZE</a></span></dt> +<dt><span class="section"><a href="refe.html#typeof.regtype">REGISTER_TYPE</a></span></dt> +<dt><span class="section"><a href="refe.html#typeof.regtemp">REGISTER_TEMPLATE</a></span></dt> +<dt><span class="section"><a href="refe.html#typeof.temp">TEMPLATE</a></span></dt> +<dt><span class="section"><a href="refe.html#typeof.typo">TYPEOF, TYPEOF_TPL</a></span></dt> +<dt><span class="section"><a href="refe.html#typeof.typn">TYPEOF_NESTED_TYPEDEF, TYPEOF_NESTED_TYPEDEF_TPL</a></span></dt> +</dl></div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.auto"></a>AUTO, AUTO_TPL</h3></div></div></div> +<p> + The <code class="computeroutput"><span class="identifier">BOOST_AUTO</span></code> macro emulates + the proposed <code class="computeroutput"><span class="keyword">auto</span></code> keyword in + C++. + </p> +<h5> +<a name="auto.usage"></a> + Usage + </h5> +<pre class="programlisting"><span class="identifier">BOOST_AUTO</span><span class="special">(</span><span class="identifier">var</span><span class="special">,</span><span class="identifier">expr</span><span class="special">)</span> +<span class="identifier">BOOST_AUTO_TPL</span><span class="special">(</span><span class="identifier">var</span><span class="special">,</span><span class="identifier">expr</span><span class="special">)</span> +</pre> +<div class="variablelist"> +<p class="title"><b>Arguments</b></p> +<dl> +<dt><span class="term">var</span></dt> +<dd><p> + a variable to be initialized with the expression + </p></dd> +<dt><span class="term">expr</span></dt> +<dd><p> + a valid c++ expression + </p></dd> +</dl> +</div> +<h5> +<a name="auto.remarks"></a> + Remarks + </h5> +<p> + If you want to use <code class="computeroutput"><span class="keyword">auto</span></code> in a + template-context, use <code class="computeroutput"><span class="identifier">BOOST_AUTO_TPL</span><span class="special">(</span><span class="identifier">expr</span><span class="special">)</span></code>, + which takes care of the <code class="computeroutput"><span class="keyword">typename</span></code> + keyword inside the <code class="computeroutput"><span class="keyword">auto</span></code> expression. + </p> +<h5> +<a name="auto.sample_code"></a> + Sample Code + </h5> +<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> +<span class="special">{</span> + <span class="identifier">length</span><span class="special">::</span><span class="identifier">meter</span> <span class="identifier">a</span><span class="special">(</span><span class="number">5</span><span class="special">);</span> + <span class="identifier">force</span><span class="special">::</span><span class="identifier">newton</span> <span class="identifier">b</span><span class="special">(</span><span class="number">6</span><span class="special">);</span> + <span class="identifier">BOOST_AUTO</span><span class="special">(</span><span class="identifier">c</span><span class="special">,</span> <span class="identifier">a</span> <span class="special">*</span> <span class="identifier">b</span><span class="special">);</span> +<span class="special">}</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.compl"></a>COMPLIANT</h3></div></div></div> +<p> + The <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_COMPLIANT</span></code> + macro can be used to force the emulation mode. Define it if your compiler + by default uses another mode, such as native <code class="computeroutput"><span class="identifier">typeof</span></code> + or Microsoft-specific trick, but you want to use the emulation mode, for + example for portability reasons. + </p> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.incr"></a>INCREMENT_REGISTRATION_GROUP</h3></div></div></div> +<p> + The <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP</span></code> + macro ensures that type registrations in different header files receive unique + identifiers. + </p> +<h5> +<a name="incr.usage"></a> + Usage + </h5> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="identifier">BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP</span><span class="special">()</span> +</pre> +<h5> +<a name="incr.remarks"></a> + Remarks + </h5> +<p> + specified once in every cpp/hpp file where any registration is performed, + before any registration. + </p> +<h5> +<a name="incr.sample_code"></a> + Sample Code + </h5> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="identifier">BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP</span><span class="special">()</span> + +<span class="keyword">class</span> <span class="identifier">X</span><span class="special">;</span> +<span class="identifier">BOOST_TYPEOF_REGISTER_TYPE</span><span class="special">(</span><span class="identifier">X</span><span class="special">)</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.inte"></a>INTEGRAL</h3></div></div></div> +<p> + The <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_INTEGRAL</span></code> + macro is used when registering an integral template parameter using <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span></code>. + </p> +<p> + Useful for <code class="computeroutput"><span class="keyword">enum</span></code>s and dependent + integral template parameters. + </p> +<h5> +<a name="inte.usage"></a> + Usage + </h5> +<pre class="programlisting"><span class="identifier">BOOST_TYPEOF_INTEGRAL</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span> +</pre> +<div class="variablelist"> +<p class="title"><b>Arguments</b></p> +<dl> +<dt><span class="term">x</span></dt> +<dd><p> + a fully qualified integral type or enum + </p></dd> +</dl> +</div> +<h5> +<a name="inte.remarks"></a> + Remarks + </h5> +<p> + A short syntax has been implemented for the built in types (int, bool, long, + unsigned long, etc.) Other non-type template parameters (e.g. pointer to + member) are not supported. + </p> +<h5> +<a name="inte.sample_code"></a> + Sample Code + </h5> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="identifier">BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP</span><span class="special">()</span> + +<span class="keyword">namespace</span> <span class="identifier">foo</span> +<span class="special">{</span> + <span class="keyword">enum</span> <span class="identifier">color</span> <span class="special">{</span><span class="identifier">red</span><span class="special">,</span> <span class="identifier">green</span><span class="special">,</span> <span class="identifier">blue</span><span class="special">};</span> + + <span class="keyword">template</span><span class="special"><</span><span class="identifier">color</span> <span class="identifier">C0</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">T1</span><span class="special">></span> + <span class="keyword">class</span> <span class="identifier">class_with_enum</span> <span class="special">{};</span> + + <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">T0</span><span class="special">,</span><span class="identifier">T0</span> <span class="identifier">I1</span><span class="special">></span> + <span class="keyword">class</span> <span class="identifier">class_with_dependent_non_type</span> <span class="special">{};</span> +<span class="special">}</span> + +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">foo</span><span class="special">::</span><span class="identifier">class_with_enum</span><span class="special">,</span> + <span class="special">(</span><span class="identifier">BOOST_TYPEOF_INTEGRAL</span><span class="special">(</span><span class="identifier">foo</span><span class="special">::</span><span class="identifier">color</span><span class="special">))</span> + <span class="special">(</span><span class="keyword">typename</span><span class="special">)</span> + <span class="special">)</span> + +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">foo</span><span class="special">::</span><span class="identifier">class_with_dependent_non_type</span><span class="special">,</span> + <span class="special">(</span><span class="keyword">typename</span><span class="special">)</span> + <span class="special">(</span><span class="identifier">BOOST_TYPEOF_INTEGRAL</span><span class="special">(</span><span class="identifier">P0</span><span class="special">))</span> + <span class="special">)</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.limit_func"></a>LIMIT_FUNCTION_ARITY</h3></div></div></div> +<p> + The <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_LIMIT_FUNCTION_ARITY</span></code> + macro defines how many parameters are supported for functios, and applies + to functions, function pointers, function references, and member function + pointers. The default value is 10. Redefine if you want the Typeof Library + to handle functions with more parameters. + </p> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.messages"></a>MESSAGES</h3></div></div></div> +<p> + Define <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_MESSAGE</span></code> + before including boost/typeof/typeof.hpp to include messages "using + typeof emulation" and "using native typeof". By default, these + messages will not be displayed. + </p> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.limit_size"></a>LIMIT_SIZE</h3></div></div></div> +<p> + The <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_LIMIT_SIZE</span></code> + macro defines the size of the compile-time sequence used to encode a type. + The default value is 50. Increase it if you want the Typeof Library to handle + very complex types, although this possibility is limited by the maximum number + of template parameters supported by your compiler. On the other hand, if + you work only with very simple types, decreasing this number may help to + boost compile-time performance. + </p> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.regtype"></a>REGISTER_TYPE</h3></div></div></div> +<p> + The <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_REGISTER_TYPE</span></code> + macro informs the Typeof Library about the existence of a type + </p> +<h5> +<a name="regtype.usage"></a> + Usage + </h5> +<pre class="programlisting"><span class="identifier">BOOST_TYPEOF_REGISTER_TYPE</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span> +</pre> +<div class="variablelist"> +<p class="title"><b>Arguments</b></p> +<dl> +<dt><span class="term">x</span></dt> +<dd><p> + a fully qualified type + </p></dd> +</dl> +</div> +<h5> +<a name="regtype.remarks"></a> + Remarks + </h5> +<p> + Must be used in the global namespace + </p> +<h5> +<a name="regtype.sample_code"></a> + Sample Code + </h5> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="identifier">BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP</span><span class="special">()</span> + +<span class="keyword">namespace</span> <span class="identifier">foo</span> +<span class="special">{</span> + <span class="keyword">class</span> <span class="identifier">bar</span> <span class="special">{};</span> + <span class="keyword">enum</span> <span class="identifier">color</span> <span class="special">{</span><span class="identifier">red</span><span class="special">,</span> <span class="identifier">green</span><span class="special">,</span> <span class="identifier">blue</span><span class="special">};</span> +<span class="special">}</span> + +<span class="identifier">BOOST_TYPEOF_REGISTER_TYPE</span><span class="special">(</span><span class="identifier">foo</span><span class="special">::</span><span class="identifier">bar</span><span class="special">)</span> +<span class="identifier">BOOST_TYPEOF_REGISTER_TYPE</span><span class="special">(</span><span class="identifier">foo</span><span class="special">::</span><span class="identifier">color</span><span class="special">)</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.regtemp"></a>REGISTER_TEMPLATE</h3></div></div></div> +<p> + The <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span></code> + macro informs the Typeof Library about the existence of a template and describes + its parameters + </p> +<h5> +<a name="regtemp.usage"></a> + Usage + </h5> +<pre class="programlisting"><span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">x</span><span class="special">,</span> <span class="identifier">n</span><span class="special">)</span> +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">x</span><span class="special">,</span> <span class="identifier">seq</span><span class="special">)</span> +</pre> +<div class="variablelist"> +<p class="title"><b>Arguments</b></p> +<dl> +<dt><span class="term">x</span></dt> +<dd><p> + a fully qualified template + </p></dd> +<dt><span class="term">n</span></dt> +<dd><p> + the number of template arguments. Only valid if all template arguments + are typenames + </p></dd> +<dt><span class="term">seq</span></dt> +<dd><p> + a sequence of template arguments. Must be used when integral or template + template parameters are present + </p></dd> +</dl> +</div> +<h5> +<a name="regtemp.remarks"></a> + Remarks + </h5> +<p> + Must be used in the global namespace. + </p> +<p> + The library allows registration of templates with type, integral, and template + template parameters: + </p> +<div class="itemizedlist"><ul class="itemizedlist" type="disc"> +<li class="listitem"> + A type template parameter is described by the <code class="computeroutput"><span class="special">(</span><span class="keyword">class</span><span class="special">)</span></code> + or <code class="computeroutput"><span class="special">(</span><span class="keyword">typename</span><span class="special">)</span></code> sequence element + </li> +<li class="listitem"> + A template parameter of a well-known integral type can be described by + simply supplying its type, like <code class="computeroutput"><span class="special">(</span><span class="keyword">unsigned</span> <span class="keyword">int</span><span class="special">)</span></code>. The following well-known integral types + are supported: + <div class="itemizedlist"><ul class="itemizedlist" type="circle"> +<li class="listitem"> + <code class="computeroutput"><span class="special">[</span><span class="keyword">signed</span><span class="special">/</span><span class="keyword">unsigned</span><span class="special">]</span> <span class="keyword">char</span></code> + </li> +<li class="listitem"> + <code class="computeroutput"><span class="special">[</span><span class="keyword">unsigned</span><span class="special">]</span> <span class="keyword">short</span></code> + </li> +<li class="listitem"> + <code class="computeroutput"><span class="special">[</span><span class="keyword">unsigned</span><span class="special">]</span> <span class="keyword">int</span></code> + </li> +<li class="listitem"> + <code class="computeroutput"><span class="special">[</span><span class="keyword">unsigned</span><span class="special">]</span> <span class="keyword">long</span></code> + </li> +<li class="listitem"> + <code class="computeroutput"><span class="keyword">unsigned</span></code> + </li> +<li class="listitem"> + <code class="computeroutput"><span class="keyword">bool</span></code> + </li> +<li class="listitem"> + <code class="computeroutput"><span class="identifier">size_t</span></code> + </li> +</ul></div> + </li> +<li class="listitem"> + Enums and typedefs of integral types, need to be described explicitly + with the <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_INTEGRAL</span></code> + macro, like <code class="computeroutput"><span class="special">(</span><span class="identifier">BOOST_TYPEOF_INTEGRAL</span><span class="special">(</span><span class="identifier">MyEnum</span><span class="special">))</span></code> + </li> +<li class="listitem"> + Template template parameters are described with the <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_TEMPLATE</span></code> + macro, like: <code class="computeroutput"><span class="special">(</span><span class="identifier">BOOST_TYPEOF_TEMPLATE</span><span class="special">((</span><span class="keyword">class</span><span class="special">)(</span><span class="keyword">unsigned</span> <span class="keyword">int</span><span class="special">)))</span></code>. + In case of all type parameters this can be shortened to something like + <code class="computeroutput"><span class="special">(</span><span class="identifier">BOOST_TYPEOF_TEMPLATE</span><span class="special">(</span><span class="number">2</span><span class="special">))</span></code>. + The nested template template parameters are not supported. + </li> +</ul></div> +<h5> +<a name="regtemp.sample_code"></a> + Sample Code + </h5> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="identifier">BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP</span><span class="special">()</span> + +<span class="keyword">namespace</span> <span class="identifier">foo</span> +<span class="special">{</span> + <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">T0</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">T1</span><span class="special">></span> + <span class="keyword">class</span> <span class="identifier">simple_template</span> <span class="special">{};</span> + + <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">T0</span><span class="special">,</span> <span class="keyword">int</span> <span class="identifier">I1</span><span class="special">></span> + <span class="keyword">class</span> <span class="identifier">class_with_integral_constant</span> <span class="special">{};</span> +<span class="special">}</span> + +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">foo</span><span class="special">::</span><span class="identifier">simple_template</span><span class="special">,</span> <span class="number">2</span><span class="special">)</span> +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">foo</span><span class="special">::</span><span class="identifier">class_with_integral_constant</span><span class="special">,</span> <span class="special">(</span><span class="keyword">typename</span><span class="special">)(</span><span class="keyword">int</span><span class="special">))</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.temp"></a>TEMPLATE</h3></div></div></div> +<p> + The <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_TEMPLATE</span></code> + macro is used when registering template template parameters using <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span></code>. + </p> +<h5> +<a name="temp.usage"></a> + Usage + </h5> +<pre class="programlisting"><span class="identifier">BOOST_TYPEOF_TEMPLATE</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span> +<span class="identifier">BOOST_TYPEOF_TEMPLATE</span><span class="special">(</span><span class="identifier">seq</span><span class="special">)</span> +</pre> +<div class="variablelist"> +<p class="title"><b>Arguments</b></p> +<dl> +<dt><span class="term">n</span></dt> +<dd><p> + the number of template arguments. Only valid if all template arguments + are typenames + </p></dd> +<dt><span class="term">seq</span></dt> +<dd><p> + a sequence of template arguments. Must be used when there are integral + constants in the nested template + </p></dd> +</dl> +</div> +<h5> +<a name="temp.remarks"></a> + Remarks + </h5> +<p> + Can not be used to register nested template template parameters. + </p> +<h5> +<a name="temp.sample_code"></a> + Sample Code + </h5> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="identifier">BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP</span><span class="special">()</span> + +<span class="keyword">namespace</span> <span class="identifier">foo</span> +<span class="special">{</span> + <span class="keyword">enum</span> <span class="identifier">color</span> <span class="special">{</span><span class="identifier">red</span><span class="special">,</span> <span class="identifier">green</span><span class="special">,</span> <span class="identifier">blue</span><span class="special">};</span> + + <span class="keyword">template</span><span class="special"><</span><span class="identifier">color</span> <span class="identifier">C0</span><span class="special">,</span> <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span><span class="special">></span> <span class="keyword">class</span> <span class="identifier">T1</span><span class="special">></span> + <span class="keyword">class</span> <span class="identifier">nested_template_class</span> <span class="special">{};</span> + + <span class="keyword">template</span><span class="special"><</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span><span class="special">,</span> <span class="keyword">unsigned</span> <span class="keyword">char</span><span class="special">></span> <span class="keyword">class</span> <span class="identifier">T1</span><span class="special">></span> + <span class="keyword">class</span> <span class="identifier">nested_with_integral</span> <span class="special">{};</span> +<span class="special">}</span> + +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">foo</span><span class="special">::</span><span class="identifier">nested_template_class</span><span class="special">,</span> + <span class="special">(</span><span class="identifier">foo</span><span class="special">::</span><span class="identifier">color</span><span class="special">)</span> + <span class="special">(</span><span class="identifier">BOOST_TYPEOF_TEMPLATE</span><span class="special">(</span><span class="number">1</span><span class="special">))</span> + <span class="special">)</span> + +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">foo</span><span class="special">::</span><span class="identifier">nested_with_integral</span><span class="special">,</span> + <span class="special">(</span><span class="identifier">BOOST_TYPEOF_TEMPLATE</span><span class="special">((</span><span class="keyword">typename</span><span class="special">)(</span><span class="keyword">unsigned</span> <span class="keyword">char</span><span class="special">)))</span> + <span class="special">)</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.typo"></a>TYPEOF, TYPEOF_TPL</h3></div></div></div> +<p> + The <code class="computeroutput"><span class="identifier">BOOST_TYPEOF</span></code> macro calculates + the type of an expression, but removes the top-level qualifiers, <code class="computeroutput"><span class="keyword">const</span><span class="special">&</span></code> + </p> +<h5> +<a name="typo.usage"></a> + Usage + </h5> +<pre class="programlisting"><span class="identifier">BOOST_TYPEOF</span><span class="special">(</span><span class="identifier">expr</span><span class="special">)</span> +<span class="identifier">BOOST_TYPEOF_TPL</span><span class="special">(</span><span class="identifier">expr</span><span class="special">)</span> +</pre> +<div class="variablelist"> +<p class="title"><b>Arguments</b></p> +<dl> +<dt><span class="term">expr</span></dt> +<dd><p> + a valid c++ expression that can be bound to const T& + </p></dd> +</dl> +</div> +<h5> +<a name="typo.remarks"></a> + Remarks + </h5> +<p> + If you want to use <code class="computeroutput"><span class="identifier">typeof</span></code> + in a template-context, use <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_TPL</span><span class="special">(</span><span class="identifier">expr</span><span class="special">)</span></code>, + which takes care of <code class="computeroutput"><span class="keyword">typename</span></code> + inside the <code class="computeroutput"><span class="identifier">typeof</span></code> expression. + </p> +<h5> +<a name="typo.sample_code"></a> + Sample Code + </h5> +<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">A</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">B</span><span class="special">></span> +<span class="keyword">struct</span> <span class="identifier">result_of_conditional</span> +<span class="special">{</span> + <span class="keyword">typedef</span> <span class="identifier">BOOST_TYPEOF_TPL</span><span class="special">(</span><span class="keyword">true</span><span class="special">?</span><span class="identifier">A</span><span class="special">():</span><span class="identifier">B</span><span class="special">())</span> <span class="identifier">type</span><span class="special">;</span> +<span class="special">};</span> + +<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">A</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">B</span><span class="special">></span> +<span class="identifier">result_of_conditional</span><span class="special"><</span><span class="identifier">A</span><span class="special">,</span> <span class="identifier">B</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">min</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">A</span><span class="special">&</span> <span class="identifier">a</span><span class="special">,</span><span class="keyword">const</span> <span class="identifier">B</span><span class="special">&</span> <span class="identifier">b</span><span class="special">)</span> +<span class="special">{</span> + <span class="keyword">return</span> <span class="identifier">a</span> <span class="special"><</span> <span class="identifier">b</span> <span class="special">?</span> <span class="identifier">a</span> <span class="special">:</span> <span class="identifier">b</span><span class="special">;</span> +<span class="special">}</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="typeof.typn"></a>TYPEOF_NESTED_TYPEDEF, TYPEOF_NESTED_TYPEDEF_TPL</h3></div></div></div> +<p> + The <code class="computeroutput"><span class="identifier">TYPEOF_NESTED_TYPEDEF</span></code> + macro works in much the same way as the 'TYPEOF' macro does, but workarounds + several compiler deficiencies. + </p> +<h5> +<a name="typn.usage"></a> + Usage + </h5> +<pre class="programlisting"><span class="identifier">BOOST_TYPEOF_NESTED_TYPEDEF</span><span class="special">(</span><span class="identifier">name</span><span class="special">,</span><span class="identifier">expr</span><span class="special">)</span> +<span class="identifier">BOOST_TYPEOF_NESTED_TYPEDEF_TPL</span><span class="special">(</span><span class="identifier">name</span><span class="special">,</span><span class="identifier">expr</span><span class="special">)</span> +</pre> +<div class="variablelist"> +<p class="title"><b>Arguments</b></p> +<dl> +<dt><span class="term">name</span></dt> +<dd> +<p> + a valid identifier to nest the typeof operation inside + </p> +<p> + expr + </p> +<p> + a valid c++ expression that can be bound to const T& + </p> +</dd> +</dl> +</div> +<h5> +<a name="typn.remarks"></a> + Remarks + </h5> +<p> + 'typeof_nested_typedef' nests the 'typeof' operation inside a struct. By + doing this, the 'typeof' operation can be split into two steps, deconfusing + several compilers (notably VC7.1 and VC8.0) on the way. This also removes + the limitation imposed by <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_LIMIT_SIZE</span></code> + and allows you to use 'typeof' on much larger expressions. + </p> +<p> + If you want to use <code class="computeroutput"><span class="identifier">typeof_nested_typedef</span></code> + in a template-context, use <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_NESTED_TYPEDEF_TPL</span><span class="special">(</span><span class="identifier">name</span><span class="special">,</span><span class="identifier">expr</span><span class="special">)</span></code>, + which takes care of <code class="computeroutput"><span class="keyword">typename</span></code> + inside the <code class="computeroutput"><span class="identifier">typeof</span></code> expression. + </p> +<p> + 'typeof_nested_typedef' can not be used at function/block scope. + </p> +<h5> +<a name="typn.sample_code"></a> + Sample Code + </h5> +<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">A</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">B</span><span class="special">></span> +<span class="keyword">struct</span> <span class="identifier">result_of_conditional</span> +<span class="special">{</span> + <span class="identifier">BOOST_TYPEOF_NESTED_TYPEDEF_TPL</span><span class="special">(</span><span class="identifier">nested</span><span class="special">,</span><span class="keyword">true</span><span class="special">?</span><span class="identifier">A</span><span class="special">():</span><span class="identifier">B</span><span class="special">())</span> + <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">nested</span><span class="special">::</span><span class="identifier">type</span> <span class="identifier">type</span><span class="special">;</span> +<span class="special">};</span> + +<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">A</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">B</span><span class="special">></span> +<span class="identifier">result_of_conditional</span><span class="special"><</span><span class="identifier">A</span><span class="special">,</span> <span class="identifier">B</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">min</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">A</span><span class="special">&</span> <span class="identifier">a</span><span class="special">,</span><span class="keyword">const</span> <span class="identifier">B</span><span class="special">&</span> <span class="identifier">b</span><span class="special">)</span> +<span class="special">{</span> + <span class="keyword">return</span> <span class="identifier">a</span> <span class="special"><</span> <span class="identifier">b</span> <span class="special">?</span> <span class="identifier">a</span> <span class="special">:</span> <span class="identifier">b</span><span class="special">;</span> +<span class="special">}</span> +</pre> +</div> +</div> +<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> +<td align="left"></td> +<td align="right"><div class="copyright-footer">Copyright © 2004, 2005 Arkadiy Vertleyb, Peder Holt<p> + Distributed under the Boost Software License, Version 1.0. (See accompanying + file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top"> + http://www.boost.org/LICENSE_1_0.txt </a>) + </p> +</div></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="tuto.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../typeof.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="other.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +</body> +</html> diff --git a/doc/html/typeof/tuto.html b/doc/html/typeof/tuto.html new file mode 100755 index 0000000000..2ae1743dc3 --- /dev/null +++ b/doc/html/typeof/tuto.html @@ -0,0 +1,222 @@ +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> +<title>Tutorial</title> +<link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> +<meta name="generator" content="DocBook XSL Stylesheets V1.76.1"> +<link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> +<link rel="up" href="../typeof.html" title="Chapter 31. Boost.Typeof"> +<link rel="prev" href="../typeof.html" title="Chapter 31. Boost.Typeof"> +<link rel="next" href="refe.html" title="Reference"> +</head> +<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> +<table cellpadding="2" width="100%"><tr> +<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td> +<td align="center"><a href="../../../index.html">Home</a></td> +<td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td> +<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> +<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> +<td align="center"><a href="../../../more/index.htm">More</a></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="../typeof.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../typeof.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="refe.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +<div class="section"> +<div class="titlepage"><div><div><h2 class="title" style="clear: both"> +<a name="typeof.tuto"></a>Tutorial</h2></div></div></div> +<p> + To start using typeof include the typeof header: + </p> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">typeof</span><span class="special">/</span><span class="identifier">typeof</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> +</pre> +<p> + To deduce the type of an expression at compile time use the <code class="computeroutput"><span class="identifier">BOOST_TYPEOF</span></code> + macro: + </p> +<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">ex1</span> +<span class="special">{</span> + <span class="keyword">typedef</span> <span class="identifier">BOOST_TYPEOF</span><span class="special">(</span><span class="number">1</span> <span class="special">+</span> <span class="number">0.5</span><span class="special">)</span> <span class="identifier">type</span><span class="special">;</span> + + <span class="identifier">BOOST_STATIC_ASSERT</span><span class="special">((</span><span class="identifier">is_same</span><span class="special"><</span><span class="identifier">type</span><span class="special">,</span> <span class="keyword">double</span><span class="special">>::</span><span class="identifier">value</span><span class="special">));</span> +<span class="special">}</span> +</pre> +<p> + In the dependent context use <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_TPL</span></code> + instead of <code class="computeroutput"><span class="identifier">BOOST_TYPEOF</span></code>: + </p> +<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">ex2</span> +<span class="special">{</span> + <span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span> + <span class="identifier">BOOST_TYPEOF_TPL</span><span class="special">(</span><span class="identifier">T</span><span class="special">()</span> <span class="special">+</span> <span class="identifier">U</span><span class="special">())</span> <span class="identifier">add</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">t</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">U</span><span class="special">&</span> <span class="identifier">u</span><span class="special">)</span> + <span class="special">{</span> + <span class="keyword">return</span> <span class="identifier">t</span> <span class="special">+</span> <span class="identifier">u</span><span class="special">;</span> + <span class="special">};</span> + + <span class="keyword">typedef</span> <span class="identifier">BOOST_TYPEOF</span><span class="special">(</span><span class="identifier">add</span><span class="special">(</span><span class="char">'a'</span><span class="special">,</span> <span class="number">1.5</span><span class="special">))</span> <span class="identifier">type</span><span class="special">;</span> + + <span class="identifier">BOOST_STATIC_ASSERT</span><span class="special">((</span><span class="identifier">is_same</span><span class="special"><</span><span class="identifier">type</span><span class="special">,</span> <span class="keyword">double</span><span class="special">>::</span><span class="identifier">value</span><span class="special">));</span> +<span class="special">}</span> +</pre> +<p> + The above examples are possible because the Typeof Library knows about primitive + types, such as <code class="computeroutput"><span class="keyword">int</span></code>, <code class="computeroutput"><span class="keyword">double</span></code>, <code class="computeroutput"><span class="keyword">char</span></code>, + etc. The Typeof Library also knows about most types and templates defined by + the Standard C++ Library, but the appropriate headers need to be included to + take advantage of this: + </p> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">typeof</span><span class="special">/</span><span class="identifier">std</span><span class="special">/</span><span class="identifier">utility</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> + +<span class="keyword">namespace</span> <span class="identifier">ex3</span> +<span class="special">{</span> + <span class="identifier">BOOST_AUTO</span><span class="special">(</span><span class="identifier">p</span><span class="special">,</span> <span class="identifier">make_pair</span><span class="special">(</span><span class="number">1</span><span class="special">,</span> <span class="number">2</span><span class="special">));</span> + + <span class="identifier">BOOST_STATIC_ASSERT</span><span class="special">((</span><span class="identifier">is_same</span><span class="special"><</span><span class="identifier">BOOST_TYPEOF</span><span class="special">(</span><span class="identifier">p</span><span class="special">),</span> <span class="identifier">pair</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="keyword">int</span><span class="special">></span> <span class="special">>::</span><span class="identifier">value</span><span class="special">));</span> +<span class="special">}</span> +</pre> +<p> + Here <code class="computeroutput"><span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">typeof</span><span class="special">/</span><span class="identifier">std</span><span class="special">/</span><span class="identifier">utility</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code> + includes <code class="computeroutput"><span class="special"><</span><span class="identifier">utility</span><span class="special">></span></code> and contains knowledge about templates + defined there. This naming convention applies in general, for example to let + the Typeof Library handle <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span></code>, + include <code class="computeroutput"><span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">typeof</span><span class="special">/</span><span class="identifier">std</span><span class="special">/</span><span class="identifier">vector</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code>, + etc. + </p> +<p> + To deduce the type of a variable from the expression, this variable is initialized + with, use the <code class="computeroutput"><span class="identifier">BOOST_AUTO</span></code> macro + (or <code class="computeroutput"><span class="identifier">BOOST_AUTO_TPL</span></code> in a dependent + context: + </p> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">typeof</span><span class="special">/</span><span class="identifier">std</span><span class="special">/</span><span class="identifier">string</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> + +<span class="keyword">namespace</span> <span class="identifier">ex4</span> +<span class="special">{</span> + <span class="identifier">BOOST_AUTO</span><span class="special">(</span><span class="identifier">p</span><span class="special">,</span> <span class="keyword">new</span> <span class="keyword">int</span><span class="special">[</span><span class="number">20</span><span class="special">]);</span> + + <span class="identifier">BOOST_STATIC_ASSERT</span><span class="special">((</span><span class="identifier">is_same</span><span class="special"><</span><span class="identifier">BOOST_TYPEOF</span><span class="special">(</span><span class="identifier">p</span><span class="special">),</span> <span class="keyword">int</span><span class="special">*>::</span><span class="identifier">value</span><span class="special">));</span> +<span class="special">}</span> +</pre> +<p> + Both <code class="computeroutput"><span class="identifier">BOOST_TYPEOF</span></code> and <code class="computeroutput"><span class="identifier">BOOST_AUTO</span></code> strip top-level qualifiers. Therefore, + to allocate for example a reference, it has to be specified explicitly: + </p> +<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">ex5</span> +<span class="special">{</span> + <span class="identifier">string</span><span class="special">&</span> <span class="identifier">hello</span><span class="special">()</span> + <span class="special">{</span> + <span class="keyword">static</span> <span class="identifier">string</span> <span class="identifier">s</span> <span class="special">=</span> <span class="string">"hello"</span><span class="special">;</span> + <span class="keyword">return</span> <span class="identifier">s</span><span class="special">;</span> + <span class="special">}</span> + + <span class="identifier">BOOST_AUTO</span><span class="special">(&</span><span class="identifier">s</span><span class="special">,</span> <span class="identifier">hello</span><span class="special">());</span> +<span class="special">}</span> +</pre> +<p> + To better understand this syntax, note that this gets expanded into: + </p> +<pre class="programlisting"><span class="identifier">BOOST_TYPEOF</span><span class="special">(</span><span class="identifier">hello</span><span class="special">())</span> <span class="special">&</span><span class="identifier">s</span> <span class="special">=</span> <span class="identifier">hello</span><span class="special">();</span> +</pre> +<p> + If your define your own type, the Typeof Library cannot handle it unless you + let it know about this type. You tell the Typeof Library about a type (or template) + by the means of "registering" this type/template. + </p> +<p> + Any source or header file where types/templates are registered has to contain + the following line before any registration is done: + </p> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="identifier">BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP</span><span class="special">()</span> +</pre> +<p> + After this a type can be registered: + </p> +<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">ex6</span> +<span class="special">{</span> + <span class="keyword">struct</span> <span class="identifier">MyType</span> + <span class="special">{};</span> +<span class="special">}</span> + +<span class="identifier">BOOST_TYPEOF_REGISTER_TYPE</span><span class="special">(</span><span class="identifier">ex6</span><span class="special">::</span><span class="identifier">MyType</span><span class="special">)</span> +</pre> +<p> + The registration must be done from the context of global namespace; fully qualified + type name has to be used. + </p> +<p> + Any number of types can be registered in one file, each on a separate line. + </p> +<p> + Once your type is registered, the Typeof Library can handle it in any context: + </p> +<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">ex6</span> +<span class="special">{</span> + <span class="keyword">typedef</span> <span class="identifier">BOOST_TYPEOF</span><span class="special">(</span><span class="identifier">make_pair</span><span class="special">(</span><span class="number">1</span><span class="special">,</span> <span class="identifier">MyType</span><span class="special">()))</span> <span class="identifier">type</span><span class="special">;</span> + + <span class="identifier">BOOST_STATIC_ASSERT</span><span class="special">((</span><span class="identifier">is_same</span><span class="special"><</span><span class="identifier">type</span><span class="special">,</span> <span class="identifier">pair</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="identifier">MyType</span><span class="special">></span> <span class="special">>::</span><span class="identifier">value</span><span class="special">));</span> +<span class="special">}</span> +</pre> +<p> + A template is registered by specifying its fully qualified name, and describing + its parameters. In the simplest case, when all parameters are type parameters, + only their number needs to be specified: + </p> +<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">ex7</span> +<span class="special">{</span> + <span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span> + <span class="keyword">struct</span> <span class="identifier">MyTemplate</span> + <span class="special">{};</span> +<span class="special">}</span> + +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">ex7</span><span class="special">::</span><span class="identifier">MyTemplate</span><span class="special">,</span> <span class="number">2</span><span class="special">)</span> + +<span class="keyword">namespace</span> <span class="identifier">ex7</span> +<span class="special">{</span> + <span class="keyword">typedef</span> <span class="identifier">BOOST_TYPEOF</span><span class="special">(</span><span class="identifier">make_pair</span><span class="special">(</span><span class="number">1</span><span class="special">,</span> <span class="identifier">MyTemplate</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="identifier">ex6</span><span class="special">::</span><span class="identifier">MyType</span><span class="special">>()))</span> <span class="identifier">type</span><span class="special">;</span> + + <span class="identifier">BOOST_STATIC_ASSERT</span><span class="special">((</span><span class="identifier">is_same</span><span class="special"><</span><span class="identifier">type</span><span class="special">,</span> + <span class="identifier">pair</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="identifier">MyTemplate</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="identifier">ex6</span><span class="special">::</span><span class="identifier">MyType</span><span class="special">></span> <span class="special">></span> + <span class="special">>::</span><span class="identifier">value</span><span class="special">));</span> +<span class="special">}</span> +</pre> +<p> + When a template has integral template parameters, all parameters need to be + described in the preprocessor sequence: + </p> +<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">ex8</span> +<span class="special">{</span> + <span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">int</span> <span class="identifier">n</span><span class="special">></span> + <span class="keyword">struct</span> <span class="identifier">MyTemplate</span> + <span class="special">{};</span> +<span class="special">}</span> + +<span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span><span class="special">(</span><span class="identifier">ex8</span><span class="special">::</span><span class="identifier">MyTemplate</span><span class="special">,</span> <span class="special">(</span><span class="keyword">class</span><span class="special">)(</span><span class="keyword">int</span><span class="special">))</span> + +<span class="keyword">namespace</span> <span class="identifier">ex8</span> +<span class="special">{</span> + <span class="keyword">typedef</span> <span class="identifier">BOOST_TYPEOF</span><span class="special">(</span><span class="identifier">make_pair</span><span class="special">(</span><span class="number">1</span><span class="special">,</span> <span class="identifier">MyTemplate</span><span class="special"><</span><span class="identifier">ex7</span><span class="special">::</span><span class="identifier">MyTemplate</span><span class="special"><</span><span class="identifier">ex6</span><span class="special">::</span><span class="identifier">MyType</span><span class="special">,</span> <span class="keyword">int</span><span class="special">>,</span> <span class="number">0</span><span class="special">>()))</span> <span class="identifier">type</span><span class="special">;</span> + + <span class="identifier">BOOST_STATIC_ASSERT</span><span class="special">((</span><span class="identifier">is_same</span><span class="special"><</span><span class="identifier">type</span><span class="special">,</span> + <span class="identifier">pair</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="identifier">MyTemplate</span><span class="special"><</span><span class="identifier">ex7</span><span class="special">::</span><span class="identifier">MyTemplate</span><span class="special"><</span><span class="identifier">ex6</span><span class="special">::</span><span class="identifier">MyType</span><span class="special">,</span> <span class="keyword">int</span><span class="special">>,</span> <span class="number">0</span><span class="special">></span> <span class="special">></span> + <span class="special">>::</span><span class="identifier">value</span><span class="special">));</span> +<span class="special">}</span> +</pre> +<p> + Please see the reference for more details. + </p> +</div> +<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> +<td align="left"></td> +<td align="right"><div class="copyright-footer">Copyright © 2004, 2005 Arkadiy Vertleyb, Peder Holt<p> + Distributed under the Boost Software License, Version 1.0. (See accompanying + file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top"> + http://www.boost.org/LICENSE_1_0.txt </a>) + </p> +</div></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="../typeof.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../typeof.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="refe.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +</body> +</html> |