diff options
| -rw-r--r-- | Help/guide/tutorial/A Basic Starting Point.rst | 11 | ||||
| -rw-r--r-- | Help/guide/tutorial/Adding a Library.rst | 463 | ||||
| -rw-r--r-- | Help/guide/tutorial/Step2/CMakeLists.txt | 23 | ||||
| -rw-r--r-- | Help/guide/tutorial/Step2/MathFunctions/CMakeLists.txt | 2 | ||||
| -rw-r--r-- | Help/guide/tutorial/Step2/TutorialConfig.h.in | 2 | ||||
| -rw-r--r-- | Help/guide/tutorial/Step2/tutorial.cxx | 8 |
6 files changed, 433 insertions, 76 deletions
diff --git a/Help/guide/tutorial/A Basic Starting Point.rst b/Help/guide/tutorial/A Basic Starting Point.rst index 69f6748..3dac68a 100644 --- a/Help/guide/tutorial/A Basic Starting Point.rst +++ b/Help/guide/tutorial/A Basic Starting Point.rst @@ -160,7 +160,7 @@ The last command to call for a basic project is :name: CMakeLists.txt-add_executable :language: cmake :start-after: # add the executable - :end-before: # add the binary tree to the search path for include files + :end-before: # TODO 9: .. raw:: html @@ -240,7 +240,7 @@ the following: :name: tutorial.cxx-cxx11 :language: c++ :start-after: // convert input to double - :end-before: // calculate square root + :end-before: // TODO 12: .. raw:: html @@ -265,7 +265,7 @@ add the :variable:`CMAKE_CXX_STANDARD` declarations above the call to :name: CMakeLists.txt-CXX_STANDARD :language: cmake :start-after: # specify the C++ standard - :end-before: # configure a header file to pass some of the CMake settings + :end-before: # TODO 7: .. raw:: html @@ -345,7 +345,7 @@ lets us maintain a single source of data for the version number. First, we modify the ``CMakeLists.txt`` file to use the :command:`project` command to set both the project name and version number. -When the command:`project` command is called, CMake defines +When the :command:`project` command is called, CMake defines ``Tutorial_VERSION_MAJOR`` and ``Tutorial_VERSION_MINOR`` behind the scenes. .. raw:: html @@ -375,7 +375,7 @@ specified CMake variables replaced: :name: CMakeLists.txt-configure_file :language: cmake :start-after: # to the source code - :end-before: # add the executable + :end-before: # TODO 8: .. raw:: html @@ -420,6 +420,7 @@ be replaced with the corresponding version numbers from the project in :caption: TODO 10: TutorialConfig.h.in :name: TutorialConfig.h.in :language: c++ + :end-before: // TODO 13: .. raw:: html diff --git a/Help/guide/tutorial/Adding a Library.rst b/Help/guide/tutorial/Adding a Library.rst index 71755be..9b81894 100644 --- a/Help/guide/tutorial/Adding a Library.rst +++ b/Help/guide/tutorial/Adding a Library.rst @@ -1,136 +1,457 @@ Step 2: Adding a Library ======================== -Now we will add a library to our project. This library will contain our own +At this point, we have seen how to create a basic project using CMake. In this +step, we will learn how to create and use a library in our project. We will +also see how to make the use of our library optional. + +Exercise 1 - Creating a Library +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +To add a library in CMake, use the :command:`add_library` command and specify +which source files should make up the library. + +Rather than placing all of the source files in one directory, we can organize +our project with one or more subdirectories. In this case, we will create a +subdirectory specifically for our library. Here, we can add a new +``CMakeLists.txt`` file and one or more source files. In the top level +``CMakeLists.txt`` file, we will use the :command:`add_subdirectory` command +to add the subdirectory to the build. + +Once the library is created, it is connected to our executable target with +:command:`target_include_directories` and :command:`target_link_libraries`. + +Goal +---- + +Add and use a library. + +Helpful Resources +----------------- + +* :command:`add_library` +* :command:`add_subdirectory` +* :command:`target_include_directories` +* :command:`target_link_libraries` +* :variable:`PROJECT_SOURCE_DIR` + +Files to Edit +------------- + +* ``CMakeLists.txt`` +* ``tutorial.cxx`` +* ``MathFunctions/CMakeLists.txt`` + +Getting Started +--------------- + +In this exercise, we will add a library to our project that contains 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``. This directory already contains a header file, -``MathFunctions.h``, and a source file ``mysqrt.cxx``. The source file has one -function called ``mysqrt`` that provides similar functionality to the -compiler's ``sqrt`` function. +For this tutorial we will put the library into a subdirectory called +``MathFunctions``. This directory already contains a header file, +``MathFunctions.h``, and a source file ``mysqrt.cxx``. We will not need to +modify either of these files. The source file has one function called +``mysqrt`` that provides similar functionality to the compiler's ``sqrt`` +function. + +From the ``Help/guide/tutorial/Step2`` directory, start with ``TODO 1`` and +complete through ``TODO 6``. + +First, fill in the one line ``CMakeLists.txt`` in the ``MathFunctions`` +subdirectory. + +Next, edit the top level ``CMakeLists.txt``. + +Finally, use the newly created ``MathFunctions`` library in ``tutorial.cxx`` + +Build and Run +------------- + +Run the :manual:`cmake <cmake(1)>` executable or the +:manual:`cmake-gui <cmake-gui(1)>` to configure the project and then build it +with your chosen build tool. + +Below is a refresher of what that looks like from the command line: + +.. code-block:: console + + mkdir Step2_build + cd Step2_build + cmake ../Step2 + cmake --build . + +Try to use the newly built ``Tutorial`` and ensure that it is still +producing accurate square root values. + +Solution +-------- + +In the ``CMakeLists.txt`` file in the ``MathFunctions`` directory, we create +a library target called ``MathFunctions`` with :command:`add_library`. The +source file for the library is passed as an argument to +:command:`add_library`. This looks like the following line: -Add the following one line ``CMakeLists.txt`` file to the ``MathFunctions`` -directory: +.. raw:: html + + <details><summary>TODO 1: Click to show/hide answer</summary> .. literalinclude:: Step3/MathFunctions/CMakeLists.txt - :caption: MathFunctions/CMakeLists.txt - :name: MathFunctions/CMakeLists.txt + :caption: TODO 1: MathFunctions/CMakeLists.txt + :name: MathFunctions/CMakeLists.txt-add_library :language: cmake +.. raw:: html + + </details> + To make use of the new library we will add an :command:`add_subdirectory` call in the top-level ``CMakeLists.txt`` file so that the library will get -built. We add the new library to the executable, and add ``MathFunctions`` as -an include directory so that the ``MathFunctions.h`` header file can be found. -The last few lines of the top-level ``CMakeLists.txt`` file should now look -like: +built. + +.. raw:: html + + <details><summary>TODO 2: Click to show/hide answer</summary> + +.. code-block:: cmake + :caption: TODO 2: CMakeLists.txt + :name: CMakeLists.txt-add_subdirectory + + add_subdirectory(MathFunctions) + +.. raw:: html + + </details> + +Next, the new library target is linked to the executable target using +:command:`target_link_libraries`. + +.. raw:: html + + <details><summary>TODO 3: Click to show/hide answer</summary> + +.. code-block:: cmake + :caption: TODO 3: CMakeLists.txt + :name: CMakeLists.txt-target_link_libraries + + target_link_libraries(Tutorial PUBLIC MathFunctions) + +.. raw:: html + + </details> + +Finally we need to specify the library's header file location. Modify +:command:`target_include_directories` to add the ``MathFunctions`` subdirectory +as an include directory so that the ``MathFunctions.h`` header file can be +found. + +.. raw:: html + + <details><summary>TODO 4: Click to show/hide answer</summary> .. code-block:: cmake - :caption: CMakeLists.txt - :name: CMakeLists.txt-add_subdirectory + :caption: TODO 4: CMakeLists.txt + :name: CMakeLists.txt-target_include_directories-step2 + + target_include_directories(Tutorial PUBLIC + "${PROJECT_BINARY_DIR}" + "${PROJECT_SOURCE_DIR}/MathFunctions" + ) + +.. raw:: html + + </details> + +Now let's use our library. In ``tutorial.cxx``, include ``MathFunctions.h``: + +.. raw:: html + + <details><summary>TODO 5: Click to show/hide answer</summary> - # add the MathFunctions library - add_subdirectory(MathFunctions) +.. code-block:: c++ + :caption: TODO 5 : tutorial.cxx + :name: tutorial.cxx-include_MathFunctions.h - # add the executable - add_executable(Tutorial tutorial.cxx) + #include "MathFunctions.h" - target_link_libraries(Tutorial PUBLIC MathFunctions) +.. raw:: html - # add the binary tree to the search path for include files - # so that we will find TutorialConfig.h - target_include_directories(Tutorial PUBLIC - "${PROJECT_BINARY_DIR}" - "${PROJECT_SOURCE_DIR}/MathFunctions" - ) + </details> -Now let us make the ``MathFunctions`` library optional. While for the tutorial +Lastly, replace ``sqrt`` with our library function ``mysqrt``. + +.. raw:: html + + <details><summary>TODO 6: Click to show/hide answer</summary> + +.. code-block:: c++ + :caption: TODO 6 : tutorial.cxx + :name: tutorial.cxx-call_mysqrt + + const double outputValue = mysqrt(inputValue); + +.. raw:: html + + </details> + +Exercise 2 - Making Our Library Optional +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Now let us make the MathFunctions library optional. While for the tutorial there really isn't any need to do so, for larger projects this is a common -occurrence. The first step is to add an option to the top-level -``CMakeLists.txt`` file. +occurrence. + +CMake can do this using the :command:`option` command. This gives users a +variable which they can change when configuring their cmake build. This +setting will be stored in the cache so that the user does not need to set +the value each time they run CMake on a build directory. + +Goal +---- + +Add the option to build without ``MathFunctions``. + + +Helpful Resources +----------------- + +* :command:`if` +* :command:`list` +* :command:`option` +* :command:`cmakedefine <configure_file>` + +Files to Edit +------------- + +* ``CMakeLists.txt`` +* ``tutorial.cxx`` +* ``TutorialConfig.h.in`` + +Getting Started +--------------- + +Start with the resulting files from Exercise 1. Complete ``TODO 7`` through +``TODO 13``. + +First create a variable ``MY_MATH`` using the :command:`option` command +in the top-level ``CMakeLists.txt`` file. In that same file, use that option +to determine whether to build and use the ``MathFunctions`` library. + +Then, update ``tutorial.cxx`` and ``TutorialConfig.h.in`` to use ``MY_MATH``. + +Build and Run +------------- + +Since we have our build directory already configured from Exercise 1, we can +rebuild by simply calling the following: + +.. code-block:: console + + cd ../Step2_build + cmake --build . + +Next, run the ``Tutorial`` executable on a few numbers to verify that it's +still correct. + +Now let's update the value of ``USE_MYMATH`` to ``OFF``. The easiest way is to +use the :manual:`cmake-gui <cmake-gui(1)>` or :manual:`ccmake <ccmake(1)>` +if you're in the terminal. Or, alternatively, if you want to change the +option from the command-line, try: + +.. code-block:: console + + cmake ../Step2 -DUSE_MYMATH=OFF + +Now, rebuild the code with the following: + +.. code-block:: console + + cmake --build . + +Then, run the executable again to ensure that it still works with +``USE_MYMATH`` set to ``OFF``. Which function gives better results, ``sqrt`` +or ``mysqrt``? + +Solution +-------- + +The first step is to add an option to the top-level ``CMakeLists.txt`` file. +This option will be displayed in the :manual:`cmake-gui <cmake-gui(1)>` and +:manual:`ccmake <ccmake(1)>` with a default value of ``ON`` that can be +changed by the user. + +.. raw:: html + + <details><summary>TODO 7: Click to show/hide answer</summary> .. literalinclude:: Step3/CMakeLists.txt - :caption: CMakeLists.txt + :caption: TODO 7: CMakeLists.txt :name: CMakeLists.txt-option :language: cmake :start-after: # should we use our own math functions - :end-before: # add the MathFunctions library + :end-before: # configure a header file to pass some of the CMake settings -This option will be displayed in the :manual:`cmake-gui <cmake-gui(1)>` and -:manual:`ccmake <ccmake(1)>` -with a default value of ``ON`` that can be changed by the user. This setting -will be stored in the cache so that the user does not need to set the value -each time they run CMake on a build directory. - -The next change is to make building and linking the ``MathFunctions`` library -conditional. To do this, we will create an ``if`` statement which checks the -value of the option. Inside the ``if`` block, put the -:command:`add_subdirectory` command from above with some additional list -commands to store information needed to link to the library and add the -subdirectory as an include directory in the ``Tutorial`` target. -The end of the top-level ``CMakeLists.txt`` file will now look like the -following: +.. raw:: html + + </details> + +Next, make building and linking the ``MathFunctions`` library +conditional. + +Start by creating a :command:`list` of the optional library targets for our +project. At the moment, it is just ``MathFunctions``. Let's name our list +``EXTRA_LIBS``. + +Similarly, we need to make a :command:`list` for the optional includes which +we will call ``EXTRA_INCLUDES``. In this list, we will ``APPEND`` the path of +the header file needed for our library. + +Next, create an :command:`if` statement which checks the value of +``USE_MYMATH``. Inside the :command:`if` block, put the +:command:`add_subdirectory` command from Exercise 1 with the additional +:command:`list` commands. + +When ``MY_MATH`` is ``ON``, the lists will be generated and will be added to +our project. When ``MY_MATH`` is ``OFF``, the lists stay empty. With this +strategy, we allow users to toggle ``MY_MATH`` to manipulate what library is +used in the build. + +The top-level CMakeLists.txt file will now look like the following: + +.. raw:: html + + <details><summary>TODO 8: Click to show/hide answer</summary> .. literalinclude:: Step3/CMakeLists.txt - :caption: CMakeLists.txt - :name: CMakeLists.txt-target_link_libraries-EXTRA_LIBS + :caption: TODO 8: CMakeLists.txt + :name: CMakeLists.txt-USE_MYMATH :language: cmake :start-after: # add the MathFunctions library + :end-before: # add the executable + +.. raw:: html + + </details> -Note the use of the variable ``EXTRA_LIBS`` to collect up any optional -libraries to later be linked into the executable. The variable -``EXTRA_INCLUDES`` is used similarly for optional header files. This is a -classic approach when dealing with many optional components, we will cover -the modern approach in the next step. +Now that we have these two lists, we need to update +:command:`target_link_libraries` and :command:`target_include_directories` to +use them. Changing them is fairly straightforward. + +For :command:`target_link_libraries`, we replace the written out +library names with ``EXTRA_LIBS``. This looks like the following: + +.. raw:: html + + <details><summary>TODO 9: Click to show/hide answer</summary> + +.. literalinclude:: Step3/CMakeLists.txt + :caption: TODO 9: CMakeLists.txt + :name: CMakeLists.txt-target_link_libraries-EXTRA_LIBS + :language: cmake + :start-after: add_executable(Tutorial tutorial.cxx) + :end-before: # add the binary tree to the search path for include files + +.. raw:: html + + </details> + +Then, we do the same thing with :command:`target_include_directories` and +``EXTRA_INCLUDES``. + +.. raw:: html + + <details><summary>TODO 10: Click to show/hide answer</summary> + +.. literalinclude:: Step3/CMakeLists.txt + :caption: TODO 10 : CMakeLists.txt + :name: CMakeLists.txt-target_link_libraries-EXTRA_INCLUDES + :language: cmake + :start-after: # so that we will find TutorialConfig.h + +.. raw:: html + + </details> + +Note that this is a classic approach when dealing with many components. We +will cover the modern approach in the Step 3 of the tutorial. The corresponding changes to the source code are fairly straightforward. -First, in ``tutorial.cxx``, include the ``MathFunctions.h`` header if we -need it: +First, in ``tutorial.cxx``, we include the ``MathFunctions.h`` header if +``MY_MATH`` is defined. + +.. raw:: html + + <details><summary>TODO 11: Click to show/hide answer</summary> .. literalinclude:: Step3/tutorial.cxx - :caption: tutorial.cxx + :caption: TODO 11 : tutorial.cxx :name: tutorial.cxx-ifdef-include :language: c++ :start-after: // should we include the MathFunctions header :end-before: int main -Then, in the same file, make ``USE_MYMATH`` control which square root +.. raw:: html + + </details> + +Then, in the same file, we make ``USE_MYMATH`` control which square root function is used: +.. raw:: html + + <details><summary>TODO 12: Click to show/hide answer</summary> + .. literalinclude:: Step3/tutorial.cxx - :caption: tutorial.cxx + :caption: TODO 12 : tutorial.cxx :name: tutorial.cxx-ifdef-const :language: c++ :start-after: // which square root function should we use? :end-before: std::cout << "The square root of +.. raw:: html + + </details> + Since the source code now requires ``USE_MYMATH`` we can add it to ``TutorialConfig.h.in`` with the following line: +.. raw:: html + + <details><summary>TODO 13: Click to show/hide answer</summary> + .. literalinclude:: Step3/TutorialConfig.h.in - :caption: TutorialConfig.h.in + :caption: TODO 13 : TutorialConfig.h.in :name: TutorialConfig.h.in-cmakedefine :language: c++ :lines: 4 -**Exercise**: Why is it important that we configure ``TutorialConfig.h.in`` +.. raw:: html + + </details> + +With these changes, our library is now completely optional to whoever is +building and using it. + +Bonus Question +-------------- + +Why is it important that we configure ``TutorialConfig.h.in`` after the option for ``USE_MYMATH``? What would happen if we inverted the two? -Run the :manual:`cmake <cmake(1)>` executable or the -:manual:`cmake-gui <cmake-gui(1)>` to configure the project and then build it -with your chosen build tool. Then run the built Tutorial executable. +Answer +------ -Now let's update the value of ``USE_MYMATH``. The easiest way is to use the -:manual:`cmake-gui <cmake-gui(1)>` or :manual:`ccmake <ccmake(1)>` if you're -in the terminal. Or, alternatively, if you want to change the option from the -command-line, try: +.. raw:: html -.. code-block:: console + <details><summary>Click to show/hide answer</summary> - cmake ../Step2 -DUSE_MYMATH=OFF +We configure after because ``TutorialConfig.h.in`` uses the value of +``USE_MYMATH``. If we configure the file before +calling :command:`option`, we won't be using the expected value of +``USE_MYMATH``. -Rebuild and run the tutorial again. +.. raw:: html -Which function gives better results, ``sqrt`` or ``mysqrt``? + </details> diff --git a/Help/guide/tutorial/Step2/CMakeLists.txt b/Help/guide/tutorial/Step2/CMakeLists.txt index 7aa59e9..2f7d56e 100644 --- a/Help/guide/tutorial/Step2/CMakeLists.txt +++ b/Help/guide/tutorial/Step2/CMakeLists.txt @@ -7,13 +7,36 @@ project(Tutorial VERSION 1.0) set(CMAKE_CXX_STANDARD 11) set(CMAKE_CXX_STANDARD_REQUIRED True) +# TODO 7: Create a variable MY_MATH using option and set default to ON + # configure a header file to pass some of the CMake settings # to the source code configure_file(TutorialConfig.h.in TutorialConfig.h) +# TODO 8: Use list() and APPEND to create a list of optional libraries +# called EXTRA_LIBS and a list of optional include directories called +# EXTRA_INCLUDES. Add the MathFunctions library and source directory to +# the appropriate lists. +# +# Only call add_subdirectory and only add MathFunctions specific values +# to EXTRA_LIBS and EXTRA_INCLUDES if USE_MYMATH is true. + +# TODO 2: Use add_subdirectory() to add MathFunctions to this project + # add the executable add_executable(Tutorial tutorial.cxx) +# TODO 9: Use EXTRA_LIBS instead of the MathFunctions specific values +# in target_link_libraries. + +# TODO 3: Use target_link_libraries to link the library to our executable + +# TODO 4: Add MathFunctions to Tutorial's target_include_directories() +# Hint: ${PROJECT_SOURCE_DIR} is a path to the project source. AKA This folder! + +# TODO 10: Use EXTRA_INCLUDES instead of the MathFunctions specific values +# in target_include_directories. + # add the binary tree to the search path for include files # so that we will find TutorialConfig.h target_include_directories(Tutorial PUBLIC diff --git a/Help/guide/tutorial/Step2/MathFunctions/CMakeLists.txt b/Help/guide/tutorial/Step2/MathFunctions/CMakeLists.txt new file mode 100644 index 0000000..b7779b7 --- /dev/null +++ b/Help/guide/tutorial/Step2/MathFunctions/CMakeLists.txt @@ -0,0 +1,2 @@ +# TODO 1: Add a library called MathFunctions +# Hint: You will need the add_library command diff --git a/Help/guide/tutorial/Step2/TutorialConfig.h.in b/Help/guide/tutorial/Step2/TutorialConfig.h.in index 7e4d7fa..adb4c55 100644 --- a/Help/guide/tutorial/Step2/TutorialConfig.h.in +++ b/Help/guide/tutorial/Step2/TutorialConfig.h.in @@ -1,3 +1,5 @@ // the configured options and settings for Tutorial #define Tutorial_VERSION_MAJOR @Tutorial_VERSION_MAJOR@ #define Tutorial_VERSION_MINOR @Tutorial_VERSION_MINOR@ + +// TODO 13: use cmakedefine to define MY_MATH diff --git a/Help/guide/tutorial/Step2/tutorial.cxx b/Help/guide/tutorial/Step2/tutorial.cxx index 53b0810..f83aa7e 100644 --- a/Help/guide/tutorial/Step2/tutorial.cxx +++ b/Help/guide/tutorial/Step2/tutorial.cxx @@ -5,6 +5,10 @@ #include "TutorialConfig.h" +// TODO 11: Only include MathFunctions if MY_MATH is defined + +// TODO 5: Include MathFunctions.h + int main(int argc, char* argv[]) { if (argc < 2) { @@ -18,6 +22,10 @@ int main(int argc, char* argv[]) // convert input to double const double inputValue = std::stod(argv[1]); + // TODO 12: Use mysqrt if MY_MATH is defined and sqrt otherwise + + // TODO 6: Replace sqrt with mysqrt + // calculate square root const double outputValue = sqrt(inputValue); std::cout << "The square root of " << inputValue << " is " << outputValue |