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Diffstat (limited to 'Tests/Tutorial/Step2/directions.txt')
| -rw-r--r-- | Tests/Tutorial/Step2/directions.txt | 102 |
1 files changed, 0 insertions, 102 deletions
diff --git a/Tests/Tutorial/Step2/directions.txt b/Tests/Tutorial/Step2/directions.txt deleted file mode 100644 index bb6662c7e..000000000 --- a/Tests/Tutorial/Step2/directions.txt +++ /dev/null @@ -1,102 +0,0 @@ -# Adding a Library # - -Now we will add a library to our project. This library will contain our own -implementation for computing the square root of a number. The executable can -then use this library instead of the standard square root function provided by -the compiler. - -For this tutorial we will put the library into a subdirectory -called MathFunctions. It will have the following one line CMakeLists file: - - add_library(MathFunctions mysqrt.cxx) - -The source file mysqrt.cxx has one function called mysqrt that provides similar -functionality to the compiler’s sqrt function. To make use of the new library -we add an add_subdirectory call in the top-level CMakeLists file so that the -library will get built. We add the new library to the executable, and add the -MathFunctions as an include directory so that mqsqrt.h header file can be -found. The last few lines of the top-level CMakeLists file now look like: - - - add_subdirectory(MathFunctions) - - #add the executable - add_executable(Tutorial tutorial.cxx) - - target_link_libraries(Tutorial ${EXTRA_LIBS}) - - -Now let us make the MathFunctions library optional. While for the tutorial -there really isn’t any need to do so, but with larger projects this is a common -occurrence. The first step is to add an option to the top-level CMakeLists file. - - option (USE_MYMATH - "Use tutorial provided math implementation" ON) - -This will show up in CMake GUI and ccmake with a default value of ON that can -be changed by the user. This setting will be stored so that the user does not -need to set the value each time they run CMake on this build directory. - -The next change is to make building and linking the MathFunctions library -conditional. To do this we change the top-level CMakeLists file to look like -the following: - - cmake_minimum_required(VERSION 3.3) - project(Tutorial) - - set(CMAKE_CXX_STANDARD 11) - set(CMAKE_CXX_STANDARD_REQUIRED True) - - # the version number. - set(Tutorial_VERSION_MAJOR 1) - set(Tutorial_VERSION_MINOR 0) - - # configure a header file to pass some of the CMake settings - # to the source code - configure_file( - "${PROJECT_SOURCE_DIR}/TutorialConfig.h.in" - "${PROJECT_BINARY_DIR}/TutorialConfig.h" - ) - - # should we use our own math functions - option(USE_MYMATH "Use tutorial provided math implementation" ON) - - # add the MathFunctions library? - if(USE_MYMATH) - add_subdirectory(MathFunctions) - list(APPEND EXTRA_LIBS MathFunctions) - list(APPEND EXTRA_INCLUDES "${PROJECT_SOURCE_DIR}/MathFunctions") - endif(USE_MYMATH) - - # add the executable - add_executable(Tutorial tutorial.cxx) - - target_link_libraries(Tutorial ${EXTRA_LIBS}) - - # add the binary tree to the search path for include files - # so that we will find TutorialConfig.h - target_include_directories(Tutorial PUBLIC - "${PROJECT_BINARY_DIR}" - ${EXTRA_INCLUDES} - ) - -Note the use of the variables EXTRA_LIBS, and EXTRA_INCLUDES to collect -up any optional libraries to later be linked into the executable. This is a -classic approach when dealing with many optional components, we will cover the -modern approach in the next step. For now the corresponding changes to the -source code are fairly straightforward and leave us with: - - #ifdef USE_MYMATH - double outputValue = mysqrt(inputValue); - #else - double outputValue = sqrt(inputValue); - #endif - -Since the source code now requires USE_MYMATH we can add it to the -TutorialConfig.h.in. Simply add the following line: - #cmakedefine USE_MYMATH - -Run cmake or cmake-gui to configure the project and then build it with your -chosen build tool and then run the built Tutorial executable. - -Which function gives better results, Step1’s sqrt or Step2’s mysqrt? |