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Tutorial: Add links to relevant CMake documentation

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Add links for commands, properties and variables.
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Betsy McPhail
2019-12-04 13:13:09 -05:00
parent d4d11b1707
commit 3a510a47b0
1 changed files with 144 additions and 125 deletions
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Help/guide/tutorial/index.rst
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@@ -45,7 +45,8 @@ The first feature we will add is to provide our executable and project with a
version number. While we could do this exclusively in the source code, using
``CMakeLists.txt`` provides more flexibility.
First, modify the ``CMakeLists.txt`` file to set the version number.
First, modify the ``CMakeLists.txt`` file to use the :command:`project` command
to set the project name and version number.
.. literalinclude:: Step2/CMakeLists.txt
:language: cmake
@@ -102,9 +103,10 @@ Next let's add some C++11 features to our project by replacing ``atof`` with
We will need to explicitly state in the CMake code that it should use the
correct flags. The easiest way to enable support for a specific C++ standard
in CMake is by using the ``CMAKE_CXX_STANDARD`` variable. For this tutorial,
set the ``CMAKE_CXX_STANDARD`` variable in the ``CMakeLists.txt`` file to 11
and ``CMAKE_CXX_STANDARD_REQUIRED`` to True:
in CMake is by using the :variable:`CMAKE_CXX_STANDARD` variable. For this
tutorial, set the :variable:`CMAKE_CXX_STANDARD` variable in the
``CMakeLists.txt`` file to 11 and :variable:`CMAKE_CXX_STANDARD_REQUIRED` to
True:
.. literalinclude:: Step2/CMakeLists.txt
:language: cmake
@@ -113,7 +115,8 @@ and ``CMAKE_CXX_STANDARD_REQUIRED`` to True:
Build and Test
--------------
Run **cmake** or **cmake-gui** to configure the project and then build it
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.
For example, from the command line we could navigate to the
@@ -156,11 +159,11 @@ directory:
.. literalinclude:: Step3/MathFunctions/CMakeLists.txt
:language: cmake
To make use of the new library we will add an ``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 ``mqsqrt.h`` header file can be found. The last few lines
of the top-level ``CMakeLists.txt`` file should now look like:
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 ``mqsqrt.h`` header file can be found. The
last few lines of the top-level ``CMakeLists.txt`` file should now look like:
.. code-block:: cmake
@@ -189,10 +192,11 @@ occurrence. The first step is to add an option to the top-level
:start-after: # should we use our own math functions
:end-before: # add the MathFunctions library
This option will be displayed in the CMake GUI and ccmake 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.
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 change the end of the top-level ``CMakeLists.txt``
@@ -234,11 +238,13 @@ Since the source code now requires ``USE_MYMATH`` we can add it to
**Exercise**: 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 **cmake** or **cmake-gui** to configure the project and then build it
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.
Use ccmake or the CMake GUI to update the value of ``USE_MYMATH``. Rebuild and
run the tutorial again. Which function gives better results, sqrt or mysqrt?
Use the :manual:`ccmake <ccmake(1)>` executable or the :manual:`cmake-gui <cmake-gui(1)>`
to update the value of ``USE_MYMATH``. Rebuild and run the tutorial again.
Which function gives better results, sqrt or mysqrt?
Adding Usage Requirements for Library (Step 3)
==============================================
@@ -248,19 +254,20 @@ link and include line while also giving more control over the transitive
property of targets inside CMake. The primary commands that leverage usage
requirements are:
- ``target_compile_definitions``
- ``target_compile_options``
- ``target_include_directories``
- ``target_link_libraries``
- :command:`target_compile_definitions`
- :command:`target_compile_options`
- :command:`target_include_directories`
- :command:`target_link_libraries`
Let's refactor our code from `Adding a Library (Step 2)`_ to use the modern
CMake approach of usage requirements. We first state that anybody linking to
MathFunctions needs to include the current source directory, while
MathFunctions itself doesn't. So this can become an ``INTERFACE`` usage
MathFunctions itself doesn't. So this can become an ``INTERFACE`` usage
requirement.
Remember ``INTERFACE`` means things that consumers require but the producer
doesn't. Add the following lines to the end of ``MathFunctions/CMakeLists.txt``:
doesn't. Add the following lines to the end of
``MathFunctions/CMakeLists.txt``:
.. literalinclude:: Step4/MathFunctions/CMakeLists.txt
:language: cmake
@@ -281,9 +288,10 @@ And here:
:language: cmake
:start-after: # so that we will find TutorialConfig.h
Once this is done, run **cmake** or **cmake-gui** to configure the project
and then build it with your chosen build tool or by using ``cmake --build .``
from the build directory.
Once this is done, 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 or by using ``cmake --build .`` from the build
directory.
Installing and Testing (Step 4)
===============================
@@ -312,16 +320,17 @@ And to the end of the top-level ``CMakeLists.txt`` we add:
That is all that is needed to create a basic local install of the tutorial.
Run **cmake** or **cmake-gui** to configure the project and then build it
with your chosen build tool. Run the install step by typing
``cmake --install .`` (introduced in 3.15, older versions of CMake must use
``make install``) from the command line, or build the ``INSTALL`` target from
an IDE. This will install the appropriate header files, libraries, and
executables.
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. Run the install step by using the ``install``
option of the :manual:`cmake <cmake(1)>` command (introduced in 3.15, older
versions of CMake must use ``make install``) from the command line, or build
the ``INSTALL`` target from an IDE. This will install the appropriate header
files, libraries, and executables.
The CMake variable ``CMAKE_INSTALL_PREFIX`` is used to determine the root of
where the files will be installed. If using ``cmake --install`` a custom
installation directory can be given via ``--prefix`` argument. For
The CMake variable :variable:`CMAKE_INSTALL_PREFIX` is used to determine the
root of where the files will be installed. If using ``cmake --install`` a
custom installation directory can be given via the ``--prefix`` argument. For
multi-configuration tools, use the ``--config`` argument to specify the
configuration.
@@ -339,25 +348,25 @@ the application is working correctly.
:start-after: # enable testing
The first test simply verifies that the application runs, does not segfault or
otherwise crash, and has a zero return value. This is the basic form of a CTest
test.
otherwise crash, and has a zero return value. This is the basic form of a
CTest test.
The next test makes use of the ``PASS_REGULAR_EXPRESSION`` test property to
verify that the output of the test contains certain strings. In this case,
verifying that the usage message is printed when an incorrect number of
arguments are provided.
The next test makes use of the :prop_test:`PASS_REGULAR_EXPRESSION` test
property to verify that the output of the test contains certain strings. In
this case, verifying that the usage message is printed when an incorrect number
of arguments are provided.
Lastly, we have a function called ``do_test`` that runs the application and
verifies that the computed square root is correct for given input. For each
invocation of ``do_test``, another test is added to the project with a name,
input, and expected results based on the passed arguments.
Rebuild the application and then cd to the binary directory and run
``ctest -N`` and ``ctest -VV``. For multi-config generators (e.g. Visual
Studio), the configuration type must be specified. To run tests in Debug mode,
for example, use ``ctest -C Debug -VV`` from the build directory (not the
Debug subdirectory!). Alternatively, build the ``RUN_TESTS`` target from the
IDE.
Rebuild the application and then cd to the binary directory and run the
:manual:`ctest <ctest(1)>` executable: ``ctest -N`` and ``ctest -VV``. For
multi-config generators (e.g. Visual Studio), the configuration type must be
specified. To run tests in Debug mode, for example, use ``ctest -C Debug -VV``
from the build directory (not the Debug subdirectory!). Alternatively, build
the ``RUN_TESTS`` target from the IDE.
Adding System Introspection (Step 5)
====================================
@@ -370,7 +379,7 @@ tutorial assume that they are not common.
If the platform has ``log`` and ``exp`` then we will use them to compute the
square root in the ``mysqrt`` function. We first test for the availability of
these functions using the ``CheckSymbolExists`` module in the top-level
these functions using the :module:`CheckSymbolExists` module in the top-level
``CMakeLists.txt``. We're going to use the new defines in
``TutorialConfig.h.in``, so be sure to set them before that file is configured.
@@ -398,12 +407,13 @@ code (don't forget the ``#endif`` before returning the result!):
:start-after: // if we have both log and exp then use them
:end-before: // do ten iterations
Run **cmake** or **cmake-gui** to configure the project and then build it
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 and run the Tutorial executable.
You will notice that we're not using ``log`` and ``exp``, even if we think they
should be available. We should realize quickly that we have forgotten to include
``TutorialConfig.h`` in ``mysqrt.cxx``.
should be available. We should realize quickly that we have forgotten to
include ``TutorialConfig.h`` in ``mysqrt.cxx``.
We will also need to update ``MathFunctions/CMakeLists.txt`` so ``mysqrt.cxx``
knows where this file is located:
@@ -415,10 +425,10 @@ knows where this file is located:
PRIVATE ${CMAKE_BINARY_DIR}
)
After making this update, go ahead and build the project again and run the built
Tutorial executable. If ``log`` and ``exp`` are still not being used, open the
generated ``TutorialConfig.h`` file from the build directory. Maybe they aren't
available on the current system?
After making this update, go ahead and build the project again and run the
built Tutorial executable. If ``log`` and ``exp`` are still not being used,
open the generated ``TutorialConfig.h`` file from the build directory. Maybe
they aren't available on the current system?
Which function gives better results now, sqrt or mysqrt?
@@ -427,7 +437,7 @@ Specify Compile Definition
Is there a better place for us to save the ``HAVE_LOG`` and ``HAVE_EXP`` values
other than in ``TutorialConfig.h``? Let's try to use
``target_compile_definitions``.
:command:`target_compile_definitions`.
First, remove the defines from ``TutorialConfig.h.in``. We no longer need to
include ``TutorialConfig.h`` from ``mysqrt.cxx`` or the extra include in
@@ -460,8 +470,8 @@ First, let's remove the check for the ``log`` and ``exp`` functions in
``HAVE_EXP`` from ``mysqrt.cxx``. At the same time, we can remove
:code:`#include <cmath>`.
In the ``MathFunctions`` subdirectory, a new source file named ``MakeTable.cxx``
has been provided to generate the table.
In the ``MathFunctions`` subdirectory, a new source file named
``MakeTable.cxx`` has been provided to generate the table.
After reviewing the file, we can see that the table is produced as valid C++
code and that the output filename is passed in as an argument.
@@ -510,7 +520,8 @@ Now let's use the generated table. First, modify ``mysqrt.cxx`` to include
:language: c++
:start-after: // a hack square root calculation using simple operations
Run **cmake** or **cmake-gui** to configure the project and then build it
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.
When this project is built it will first build the ``MakeTable`` executable.
@@ -530,26 +541,28 @@ previously in `Installing and Testing (Step 4)`_ , where we were
installing the binaries that we had built from the source code. In this
example we will be building installation packages that support binary
installations and package management features. To accomplish this we will use
CPack to create platform specific installers. Specifically we need to add
a few lines to the bottom of our top-level ``CMakeLists.txt`` file.
CPack to create platform specific installers. Specifically we need to add a
few lines to the bottom of our top-level ``CMakeLists.txt`` file.
.. literalinclude:: Step8/CMakeLists.txt
:language: cmake
:start-after: # setup installer
That is all there is to it. We start by including
``InstallRequiredSystemLibraries``. This module will include any runtime
libraries that are needed by the project for the current platform. Next we
set some CPack variables to where we have stored the license and version
:module:`InstallRequiredSystemLibraries`. This module will include any runtime
libraries that are needed by the project for the current platform. Next we set
some CPack variables to where we have stored the license and version
information for this project. The version information was set earlier in this
tutorial and the ``license.txt`` has been included in the top-level source
directory for this step.
Finally we include the CPack module which will use these variables and some
other properties of the current system to setup an installer.
Finally we include the :module:`CPack module <CPack>` which will use these
variables and some other properties of the current system to setup an
installer.
The next step is to build the project in the usual manner and then run
CPack on it. To build a binary distribution, from the binary directory run:
The next step is to build the project in the usual manner and then run the
:manual:`cpack <cpack(1)>` executable. To build a binary distribution, from the
binary directory run:
.. code-block:: console
@@ -571,16 +584,17 @@ To create a source distribution you would type:
Alternatively, run ``make package`` or right click the ``Package`` target and
``Build Project`` from an IDE.
Run the installer found in the binary directory. Then run the
installed executable and verify that it works.
Run the installer found in the binary directory. Then run the installed
executable and verify that it works.
Adding Support for a Dashboard (Step 8)
=======================================
Adding support for submitting our test results to a dashboard is very easy. We
Adding support for submitting our test results to a dashboard is simple. We
already defined a number of tests for our project in `Testing Support`_. Now we
just have to run those tests and submit them to a dashboard. To include support
for dashboards we include the CTest module in our top-level ``CMakeLists.txt``.
for dashboards we include the :module:`CTest` module in our top-level
``CMakeLists.txt``.
Replace:
@@ -596,8 +610,8 @@ With:
# enable dashboard scripting
include(CTest)
The CTest module will automatically call ``enable_testing()``, so
we can remove it from our CMake files.
The :module:`CTest` module will automatically call ``enable_testing()``, so we
can remove it from our CMake files.
We will also need to create a ``CTestConfig.cmake`` file in the top-level
directory where we can specify the name of the project and where to submit the
@@ -606,9 +620,11 @@ dashboard.
.. literalinclude:: Step9/CTestConfig.cmake
:language: cmake
CTest will read in this file when it runs. To create a simple dashboard you can
run **cmake** or **cmake-gui** to configure the project, but do not build it
yet. Instead, change directory to the binary tree, and then run::
The :manual:`ctest <ctest(1)>` executable will read in this file when it runs.
To create a simple dashboard you can run the :manual:`cmake <cmake(1)>`
executable or the :manual:`cmake-gui <cmake-gui(1)>` to configure the project,
but do not build it yet. Instead, change directory to the binary tree, and then
run:
ctest [-VV] -D Experimental
@@ -619,26 +635,26 @@ type must be specified::
Or, from an IDE, build the ``Experimental`` target.
``ctest`` will build and test the project and submit the results to the Kitware
public dashboard. The results of your dashboard will be uploaded to Kitware's
public dashboard here: https://my.cdash.org/index.php?project=CMakeTutorial.
The :manual:`ctest <ctest(1)>` executable will build and test the project and
submit the results to Kitware's public dashboard:
https://my.cdash.org/index.php?project=CMakeTutorial.
Mixing Static and Shared (Step 9)
=================================
In this section we will show how by using the ``BUILD_SHARED_LIBS`` variable
we can control the default behavior of ``add_library``, and allow control
over how libraries without an explicit type (``STATIC``, ``SHARED``, ``MODULE``
or ``OBJECT``) are built.
In this section we will show how the :variable:`BUILD_SHARED_LIBS` variable can
be used to control the default behavior of :command:`add_library`,
and allow control over how libraries without an explicit type (``STATIC``,
``SHARED``, ``MODULE`` or ``OBJECT``) are built.
To accomplish this we need to add ``BUILD_SHARED_LIBS`` to the top-level
``CMakeLists.txt``. We use the ``option`` command as it allows users to
optionally select if the value should be On or Off.
To accomplish this we need to add :variable:`BUILD_SHARED_LIBS` to the
top-level ``CMakeLists.txt``. We use the :command:`option` command as it allows
users to optionally select if the value should be ON or OFF.
Next we are going to refactor MathFunctions to become a real library that
encapsulates using ``mysqrt`` or ``sqrt``, instead of requiring the calling
code to do this logic. This will also mean that ``USE_MYMATH`` will not control
building MathFuctions, but instead will control the behavior of this library.
building MathFunctions, but instead will control the behavior of this library.
The first step is to update the starting section of the top-level
``CMakeLists.txt`` to look like:
@@ -680,8 +696,8 @@ Finally, update ``MathFunctions/MathFunctions.h`` to use dll export defines:
At this point, if you build everything, you will notice that linking fails
as we are combining a static library without position independent code with a
library that has position independent code. The solution to this is to
explicitly set the ``POSITION_INDEPENDENT_CODE`` target property of SqrtLibrary
to be True no matter the build type.
explicitly set the :prop_tgt:`POSITION_INDEPENDENT_CODE` target property of
SqrtLibrary to be True no matter the build type.
.. literalinclude:: Step10/MathFunctions/CMakeLists.txt
:language: cmake
@@ -694,35 +710,39 @@ Using CMake documentation can you find a helper module to simplify this?
Adding Generator Expressions (Step 10)
======================================
Generator expressions are evaluated during build system generation to produce
information specific to each build configuration.
:manual:`Generator expressions <cmake-generator-expressions(7)>` are evaluated
during build system generation to produce information specific to each build
configuration.
Generator expressions are allowed in the context of many target properties,
such as ``LINK_LIBRARIES``, ``INCLUDE_DIRECTORIES``, ``COMPILE_DEFINITIONS``
and others. They may also be used when using commands to populate those
properties, such as ``target_link_libraries()``,
``target_include_directories()``,
``target_compile_definitions()`` and others.
:manual:`Generator expressions <cmake-generator-expressions(7)>` are allowed in
the context of many target properties, such as :prop_tgt:`LINK_LIBRARIES`,
:prop_tgt:`INCLUDE_DIRECTORIES`, :prop_tgt:`COMPILE_DEFINITIONS` and others.
They may also be used when using commands to populate those properties, such as
:command:`target_link_libraries`, :command:`target_include_directories`,
:command:`target_compile_definitions` and others.
Generator expressions may be used to enable conditional linking, conditional
definitions used when compiling, conditional include directories and more.
The conditions may be based on the build configuration, target properties,
platform information or any other queryable information.
:manual:`Generator expressions <cmake-generator-expressions(7)>` may be used
to enable conditional linking, conditional definitions used when compiling,
conditional include directories and more. The conditions may be based on the
build configuration, target properties, platform information or any other
queryable information.
There are different types of generator expressions including Logical,
Informational, and Output expressions.
There are different types of
:manual:`generator expressions <cmake-generator-expressions(7)>` including
Logical, Informational, and Output expressions.
Logical expressions are used to create conditional output. The basic
expressions are the 0 and 1 expressions. A ``$<0:...>`` results in the empty
string, and ``<1:...>`` results in the content of "...". They can also be
nested.
A common usage of generator expressions is to conditionally add compiler
flags, such as those for language levels or warnings. A nice pattern is
to associate this information to an ``INTERFACE`` target allowing this
information to propagate. Lets start by constructing an ``INTERFACE``
target and specifying the required C++ standard level of ``11`` instead
of using ``CMAKE_CXX_STANDARD``.
A common usage of
:manual:`generator expressions <cmake-generator-expressions(7)>` is to
conditionally add compiler flags, such as those for language levels or
warnings. A nice pattern is to associate this information to an ``INTERFACE``
target allowing this information to propagate. Lets start by constructing an
``INTERFACE`` target and specifying the required C++ standard level of ``11``
instead of using :variable:`CMAKE_CXX_STANDARD`.
So the following code:
@@ -739,11 +759,10 @@ Would be replaced with:
:end-before: # add compiler warning flags just when building this project via
Next we add the desired compiler warning flags that we want for our
project. As warning flags vary based on the compiler we use
the ``COMPILE_LANG_AND_ID`` generator expression to control which
flags to apply given a language and a set of compiler ids as seen
below:
Next we add the desired compiler warning flags that we want for our project. As
warning flags vary based on the compiler we use the ``COMPILE_LANG_AND_ID``
generator expression to control which flags to apply given a language and a set
of compiler ids as seen below:
.. literalinclude:: Step11/CMakeLists.txt
:language: cmake
@@ -755,8 +774,8 @@ Looking at this we see that the warning flags are encapsulated inside a
project will not inherit our warning flags.
**Exercise**: Modify ``MathFunctions/CMakeLists.txt`` so that
all targets have a ``target_link_libraries()`` call to ``tutorial_compiler_flags``.
**Exercise**: Modify ``MathFunctions/CMakeLists.txt`` so that all targets have
a :command:`target_link_libraries` call to ``tutorial_compiler_flags``.
Adding Export Configuration (Step 11)
@@ -771,12 +790,12 @@ The next step is to add the necessary information so that other CMake projects
can use our project, be it from a build directory, a local install or when
packaged.
The first step is to update our ``install(TARGETS)`` commands to not only
specify a ``DESTINATION`` but also an ``EXPORT``. The ``EXPORT`` keyword
The first step is to update our :command:`install(TARGETS)` commands to not
only specify a ``DESTINATION`` but also an ``EXPORT``. The ``EXPORT`` keyword
generates and installs a CMake file containing code to import all targets
listed in the install command from the installation tree. So let's go ahead
and explicitly ``EXPORT`` the MathFunctions library by updating the
``install`` command in ``MathFunctions/CMakeLists.txt`` to look like:
listed in the install command from the installation tree. So let's go ahead and
explicitly ``EXPORT`` the MathFunctions library by updating the ``install``
command in ``MathFunctions/CMakeLists.txt`` to look like:
.. literalinclude:: Complete/MathFunctions/CMakeLists.txt
:language: cmake
@@ -806,10 +825,10 @@ you will see that CMake will generate an error that looks like:
What CMake is trying to say is that during generating the export information
it will export a path that is intrinsically tied to the current machine and
will not be valid on other machines. The solution to this is to update the
MathFunctions ``target_include_directories`` to understand that it needs
MathFunctions :command:`target_include_directories` to understand that it needs
different ``INTERFACE`` locations when being used from within the build
directory and from an install / package. This means converting the
``target_include_directories`` call for MathFunctions to look like:
:command:`target_include_directories` call for MathFunctions to look like:
.. literalinclude:: Complete/MathFunctions/CMakeLists.txt
:language: cmake
@@ -821,7 +840,7 @@ warn anymore.
At this point, we have CMake properly packaging the target information that is
required but we will still need to generate a ``MathFunctionsConfig.cmake`` so
that the CMake ``find_package`` command can find our project. So let's go
that the CMake :command:`find_package` command can find our project. So let's go
ahead and add a new file to the top-level of the project called
``Config.cmake.in`` with the following contents: