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Merge topic 'doc-developer-to-source-guide' 

a82282a08c Help/dev: Factor out a CMake Documentation Guide for developing the docs
bfbc5241e9 Help: Fix policy markup example in cmake-developer(7)
3e5a047f1a Help: Drop compile features section from cmake-developer(7) manual
06cc050c1f Help/dev: Drop 'size_t' preference from source code guide

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !2615
pull/324/head
Brad King 7 years ago
committed by Kitware Robot
parent
bd2c17d614 a82282a08c
commit
b3d1d6d895
4 changed files with 552 additions and 584 deletions
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  1. 2
      Help/dev/README.rst
  2. 538
      Help/dev/documentation.rst
  3. 10
      Help/dev/source.rst
  4. 586
      Help/manual/cmake-developer.7.rst

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Help/dev/README.rst
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@ -36,8 +36,10 @@ Developer Documentation
CMake developer documentation is provided by the following documents:
* The `CMake Source Code Guide`_.
* The `CMake Documentation Guide`_.
.. _`CMake Source Code Guide`: source.rst
.. _`CMake Documentation Guide`: documentation.rst
Maintainer Documentation
========================

538
Help/dev/documentation.rst
View File

@ -0,0 +1,538 @@
CMake Documentation Guide
*************************
The following is a guide to the CMake documentation source for developers.
See documentation on `CMake Development`_ for more information.
.. _`CMake Development`: README.rst
Help
====
The ``Help`` directory contains CMake help manual source files.
They are written using the `reStructuredText`_ markup syntax and
processed by `Sphinx`_ to generate the CMake help manuals.
.. _`reStructuredText`: http://docutils.sourceforge.net/docs/ref/rst/introduction.html
.. _`Sphinx`: http://sphinx-doc.org
Markup Constructs
-----------------
In addition to using Sphinx to generate the CMake help manuals, we
also use a C++-implemented document processor to print documents for
the ``--help-*`` command-line help options. It supports a subset of
reStructuredText markup. When authoring or modifying documents,
please verify that the command-line help looks good in addition to the
Sphinx-generated html and man pages.
The command-line help processor supports the following constructs
defined by reStructuredText, Sphinx, and a CMake extension to Sphinx.
..
Note: This list must be kept consistent with the cmRST implementation.
CMake Domain directives
Directives defined in the `CMake Domain`_ for defining CMake
documentation objects are printed in command-line help output as
if the lines were normal paragraph text with interpretation.
CMake Domain interpreted text roles
Interpreted text roles defined in the `CMake Domain`_ for
cross-referencing CMake documentation objects are replaced by their
link text in command-line help output. Other roles are printed
literally and not processed.
``code-block`` directive
Add a literal code block without interpretation. The command-line
help processor prints the block content without the leading directive
line and with common indentation replaced by one space.
``include`` directive
Include another document source file. The command-line help
processor prints the included document inline with the referencing
document.
literal block after ``::``
A paragraph ending in ``::`` followed by a blank line treats
the following indented block as literal text without interpretation.
The command-line help processor prints the ``::`` literally and
prints the block content with common indentation replaced by one
space.
``note`` directive
Call out a side note. The command-line help processor prints the
block content as if the lines were normal paragraph text with
interpretation.
``parsed-literal`` directive
Add a literal block with markup interpretation. The command-line
help processor prints the block content without the leading
directive line and with common indentation replaced by one space.
``productionlist`` directive
Render context-free grammar productions. The command-line help
processor prints the block content as if the lines were normal
paragraph text with interpretation.
``replace`` directive
Define a ``|substitution|`` replacement.
The command-line help processor requires a substitution replacement
to be defined before it is referenced.
``|substitution|`` reference
Reference a substitution replacement previously defined by
the ``replace`` directive. The command-line help processor
performs the substitution and replaces all newlines in the
replacement text with spaces.
``toctree`` directive
Include other document sources in the Table-of-Contents
document tree. The command-line help processor prints
the referenced documents inline as part of the referencing
document.
Inline markup constructs not listed above are printed literally in the
command-line help output. We prefer to use inline markup constructs that
look correct in source form, so avoid use of \\-escapes in favor of inline
literals when possible.
Explicit markup blocks not matching directives listed above are removed from
command-line help output. Do not use them, except for plain ``..`` comments
that are removed by Sphinx too.
Note that nested indentation of blocks is not recognized by the
command-line help processor. Therefore:
* Explicit markup blocks are recognized only when not indented
inside other blocks.
* Literal blocks after paragraphs ending in ``::`` but not
at the top indentation level may consume all indented lines
following them.
Try to avoid these cases in practice.
CMake Domain
------------
CMake adds a `Sphinx Domain`_ called ``cmake``, also called the
"CMake Domain". It defines several "object" types for CMake
documentation:
``command``
A CMake language command.
``generator``
A CMake native build system generator.
See the `cmake(1)`_ command-line tool's ``-G`` option.
``manual``
A CMake manual page, like the `cmake(1)`_ manual.
``module``
A CMake module.
See the `cmake-modules(7)`_ manual
and the `include()`_ command.
``policy``
A CMake policy.
See the `cmake-policies(7)`_ manual
and the `cmake_policy()`_ command.
``prop_cache, prop_dir, prop_gbl, prop_sf, prop_inst, prop_test, prop_tgt``
A CMake cache, directory, global, source file, installed file, test,
or target property, respectively. See the `cmake-properties(7)`_
manual and the `set_property()`_ command.
``variable``
A CMake language variable.
See the `cmake-variables(7)`_ manual
and the `set()`_ command.
Documentation objects in the CMake Domain come from two sources.
First, the CMake extension to Sphinx transforms every document named
with the form ``Help/<type>/<file-name>.rst`` to a domain object with
type ``<type>``. The object name is extracted from the document title,
which is expected to be of the form::
<object-name>
-------------
and to appear at or near the top of the ``.rst`` file before any other
lines starting in a letter, digit, or ``<``. If no such title appears
literally in the ``.rst`` file, the object name is the ``<file-name>``.
If a title does appear, it is expected that ``<file-name>`` is equal
to ``<object-name>`` with any ``<`` and ``>`` characters removed.
Second, the CMake Domain provides directives to define objects inside
other documents:
.. code-block:: rst
.. command:: <command-name>
This indented block documents <command-name>.
.. variable:: <variable-name>
This indented block documents <variable-name>.
Object types for which no directive is available must be defined using
the first approach above.
.. _`Sphinx Domain`: http://sphinx-doc.org/domains.html
.. _`cmake(1)`: https://cmake.org/cmake/help/latest/manual/cmake.1.html
.. _`cmake-modules(7)`: https://cmake.org/cmake/help/latest/manual/cmake-modules.7.html
.. _`cmake-policies(7)`: https://cmake.org/cmake/help/latest/manual/cmake-policies.7.html
.. _`cmake-properties(7)`: https://cmake.org/cmake/help/latest/manual/cmake-properties.7.html
.. _`cmake-variables(7)`: https://cmake.org/cmake/help/latest/manual/cmake-variables.7.html
.. _`cmake_policy()`: https://cmake.org/cmake/help/latest/command/cmake_policy.html
.. _`include()`: https://cmake.org/cmake/help/latest/command/include.html
.. _`set()`: https://cmake.org/cmake/help/latest/command/set.html
.. _`set_property()`: https://cmake.org/cmake/help/latest/command/set_property.html
Cross-References
----------------
Sphinx uses reStructuredText interpreted text roles to provide
cross-reference syntax. The `CMake Domain`_ provides for each
domain object type a role of the same name to cross-reference it.
CMake Domain roles are inline markup of the forms::
:type:`name`
:type:`text <name>`
where ``type`` is the domain object type and ``name`` is the
domain object name. In the first form the link text will be
``name`` (or ``name()`` if the type is ``command``) and in
the second form the link text will be the explicit ``text``.
For example, the code:
.. code-block:: rst
* The :command:`list` command.
* The :command:`list(APPEND)` sub-command.
* The :command:`list() command <list>`.
* The :command:`list(APPEND) sub-command <list>`.
* The :variable:`CMAKE_VERSION` variable.
* The :prop_tgt:`OUTPUT_NAME_<CONFIG>` target property.
produces:
* The `list()`_ command.
* The `list(APPEND)`_ sub-command.
* The `list() command`_.
* The `list(APPEND) sub-command`_.
* The `CMAKE_VERSION`_ variable.
* The `OUTPUT_NAME_<CONFIG>`_ target property.
Note that CMake Domain roles differ from Sphinx and reStructuredText
convention in that the form ``a<b>``, without a space preceding ``<``,
is interpreted as a name instead of link text with an explicit target.
This is necessary because we use ``<placeholders>`` frequently in
object names like ``OUTPUT_NAME_<CONFIG>``. The form ``a <b>``,
with a space preceding ``<``, is still interpreted as a link text
with an explicit target.
.. _`list()`: https://cmake.org/cmake/help/latest/command/list.html
.. _`list(APPEND)`: https://cmake.org/cmake/help/latest/command/list.html
.. _`list(APPEND) sub-command`: https://cmake.org/cmake/help/latest/command/list.html
.. _`list() command`: https://cmake.org/cmake/help/latest/command/list.html
.. _`CMAKE_VERSION`: https://cmake.org/cmake/help/latest/variable/CMAKE_VERSION.html
.. _`OUTPUT_NAME_<CONFIG>`: https://cmake.org/cmake/help/latest/prop_tgt/OUTPUT_NAME_CONFIG.html
Style
-----
Style: Section Headers
^^^^^^^^^^^^^^^^^^^^^^
When marking section titles, make the section decoration line as long as
the title text. Use only a line below the title, not above. For
example:
.. code-block:: rst
Title Text
----------
Capitalize the first letter of each non-minor word in the title.
The section header underline character hierarchy is
* ``#``: Manual group (part) in the master document
* ``*``: Manual (chapter) title
* ``=``: Section within a manual
* ``-``: Subsection or `CMake Domain`_ object document title
* ``^``: Subsubsection or `CMake Domain`_ object document section
* ``"``: Paragraph or `CMake Domain`_ object document subsection
Style: Whitespace
^^^^^^^^^^^^^^^^^
Use two spaces for indentation. Use two spaces between sentences in
prose.
Style: Line Length
^^^^^^^^^^^^^^^^^^
Prefer to restrict the width of lines to 75-80 columns. This is not a
hard restriction, but writing new paragraphs wrapped at 75 columns
allows space for adding minor content without significant re-wrapping of
content.
Style: Prose
^^^^^^^^^^^^
Use American English spellings in prose.
Style: Starting Literal Blocks
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Prefer to mark the start of literal blocks with ``::`` at the end of
the preceding paragraph. In cases where the following block gets
a ``code-block`` marker, put a single ``:`` at the end of the preceding
paragraph.
Style: CMake Command Signatures
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Command signatures should be marked up as plain literal blocks, not as
cmake ``code-blocks``.
Signatures are separated from preceding content by a section header.
That is, use:
.. code-block:: rst
... preceding paragraph.
Normal Libraries
^^^^^^^^^^^^^^^^
::
add_library(<lib> ...)
This signature is used for ...
Signatures of commands should wrap optional parts with square brackets,
and should mark list of optional arguments with an ellipsis (``...``).
Elements of the signature which are specified by the user should be
specified with angle brackets, and may be referred to in prose using
``inline-literal`` syntax.
Style: Boolean Constants
^^^^^^^^^^^^^^^^^^^^^^^^
Use "``OFF``" and "``ON``" for boolean values which can be modified by
the user, such as ``POSITION_INDEPENDENT_CODE``. Such properties
may be "enabled" and "disabled". Use "``True``" and "``False``" for
inherent values which can't be modified after being set, such as the
``IMPORTED`` property of a build target.
Style: Inline Literals
^^^^^^^^^^^^^^^^^^^^^^
Mark up references to keywords in signatures, file names, and other
technical terms with ``inline-literal`` syntax, for example:
.. code-block:: rst
If ``WIN32`` is used with :command:`add_executable`, the
:prop_tgt:`WIN32_EXECUTABLE` target property is enabled. That command
creates the file ``<name>.exe`` on Windows.
Style: Cross-References
^^^^^^^^^^^^^^^^^^^^^^^
Mark up linkable references as links, including repeats.
An alternative, which is used by wikipedia
(`<http://en.wikipedia.org/wiki/WP:REPEATLINK>`_),
is to link to a reference only once per article. That style is not used
in CMake documentation.
Style: Referencing CMake Concepts
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
If referring to a concept which corresponds to a property, and that
concept is described in a high-level manual, prefer to link to the
manual section instead of the property. For example:
.. code-block:: rst
This command creates an :ref:`Imported Target <Imported Targets>`.
instead of:
.. code-block:: rst
This command creates an :prop_tgt:`IMPORTED` target.
The latter should be used only when referring specifically to the
property.
References to manual sections are not automatically created by creating
a section, but code such as:
.. code-block:: rst
.. _`Imported Targets`:
creates a suitable anchor. Use an anchor name which matches the name
of the corresponding section. Refer to the anchor using a
cross-reference with specified text.
Imported Targets need the ``IMPORTED`` term marked up with care in
particular because the term may refer to a command keyword, a target
property, or a concept.
Where a property, command or variable is related conceptually to others,
by for example, being related to the buildsystem description, generator
expressions or Qt, each relevant property, command or variable should
link to the primary manual, which provides high-level information. Only
particular information relating to the command should be in the
documentation of the command.
Style: Referencing CMake Domain Objects
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
When referring to `CMake Domain`_ objects such as properties, variables,
commands etc, prefer to link to the target object and follow that with
the type of object it is. For example:
.. code-block:: rst
Set the :prop_tgt:`AUTOMOC` target property to ``ON``.
Instead of
.. code-block:: rst
Set the target property :prop_tgt:`AUTOMOC` to ``ON``.
The ``policy`` directive is an exception, and the type us usually
referred to before the link:
.. code-block:: rst
If policy :policy:`CMP0022` is set to ``NEW`` the behavior is ...
However, markup self-references with ``inline-literal`` syntax.
For example, within the ``add_executable`` command documentation, use
.. code-block:: rst
``add_executable``
not
.. code-block:: rst
:command:`add_executable`
which is used elsewhere.
Modules
=======
The ``Modules`` directory contains CMake-language ``.cmake`` module files.
Module Documentation
--------------------
To document CMake module ``Modules/<module-name>.cmake``, modify
``Help/manual/cmake-modules.7.rst`` to reference the module in the
``toctree`` directive, in sorted order, as::
/module/<module-name>
Then add the module document file ``Help/module/<module-name>.rst``
containing just the line::
.. cmake-module:: ../../Modules/<module-name>.cmake
The ``cmake-module`` directive will scan the module file to extract
reStructuredText markup from comment blocks that start in ``.rst:``.
At the top of ``Modules/<module-name>.cmake``, begin with the following
license notice:
.. code-block:: cmake
# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.
After this notice, add a *BLANK* line. Then, add documentation using
a `Line Comment`_ block of the form:
.. code-block:: cmake
#.rst:
# <module-name>
# -------------
#
# <reStructuredText documentation of module>
or a `Bracket Comment`_ of the form:
::
#[[.rst:
<module-name>
-------------
<reStructuredText documentation of module>
#]]
Any number of ``=`` may be used in the opening and closing brackets
as long as they match. Content on the line containing the closing
bracket is excluded if and only if the line starts in ``#``.
Additional such ``.rst:`` comments may appear anywhere in the module file.
All such comments must start with ``#`` in the first column.
For example, a ``Findxxx.cmake`` module may contain:
::
# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.
#.rst:
# FindXxx
# -------
#
# This is a cool module.
# This module does really cool stuff.
# It can do even more than you think.
#
# It even needs two paragraphs to tell you about it.
# And it defines the following variables:
#
# * VAR_COOL: this is great isn't it?
# * VAR_REALLY_COOL: cool right?
<code>
#[========================================[.rst:
.. command:: xxx_do_something
This command does something for Xxx::
xxx_do_something(some arguments)
#]========================================]
macro(xxx_do_something)
<code>
endmacro()
Test the documentation formatting by running
``cmake --help-module <module-name>``, and also by enabling the
``SPHINX_HTML`` and ``SPHINX_MAN`` options to build the documentation.
Edit the comments until generated documentation looks satisfactory. To
have a .cmake file in this directory NOT show up in the modules
documentation, simply leave out the ``Help/module/<module-name>.rst``
file and the ``Help/manual/cmake-modules.7.rst`` toctree entry.
.. _`Line Comment`: https://cmake.org/cmake/help/latest/manual/cmake-language.7.html#line-comment
.. _`Bracket Comment`: https://cmake.org/cmake/help/latest/manual/cmake-language.7.html#bracket-comment

10
Help/dev/source.rst
View File

@ -40,13 +40,6 @@ building on older toolchains some constructs need to be handled with care:
derived from non-copyable classes must also be made non-copyable explicitly
with ``CM_DISABLE_COPY``.
* Use ``size_t`` instead of ``std::size_t``.
Various implementations have differing implementation of ``size_t``.
When assigning the result of ``.size()`` on a container for example,
the result should be assigned to ``size_t`` not to ``std::size_t``,
``unsigned int`` or similar types.
Source Tree Layout
==================
@ -56,7 +49,7 @@ The CMake source tree is organized as follows.
Shell and editor integration files.
* ``Help/``:
Documentation.
Documentation. See the `CMake Documentation Guide`_.
* ``Help/dev/``:
Developer documentation.
@ -92,4 +85,5 @@ The CMake source tree is organized as follows.
* ``Utilities/Release/``:
Scripts used to package CMake itself for distribution on ``cmake.org``.
.. _`CMake Documentation Guide`: documentation.rst
.. _`Tests/README.rst`: ../../Tests/README.rst

586
Help/manual/cmake-developer.7.rst
View File

@ -10,579 +10,20 @@ cmake-developer(7)
Introduction
============
This manual is intended for reference by developers modifying the CMake
source tree itself, and by those authoring externally-maintained modules.
This manual is intended for reference by developers working with
:manual:`cmake-language(7)` code, whether writing their own modules,
authoring their own build systems, or working on CMake itself.
See https://cmake.org/get-involved/ to get involved in development of
CMake upstream.
Adding Compile Features
=======================
CMake reports an error if a compiler whose features are known does not report
support for a particular requested feature. A compiler is considered to have
known features if it reports support for at least one feature.
When adding a new compile feature to CMake, it is therefore necessary to list
support for the feature for all CompilerIds which already have one or more
feature supported, if the new feature is available for any version of the
compiler.
When adding the first supported feature to a particular CompilerId, it is
necessary to list support for all features known to cmake (See
:variable:`CMAKE_C_COMPILE_FEATURES` and
:variable:`CMAKE_CXX_COMPILE_FEATURES` as appropriate), where available for
the compiler. Ensure that the ``CMAKE_<LANG>_STANDARD_DEFAULT`` is set to
the computed internal variable ``CMAKE_<LANG>_STANDARD_COMPUTED_DEFAULT``
for compiler versions which should be supported.
It is sensible to record the features for the most recent version of a
particular CompilerId first, and then work backwards. It is sensible to
try to create a continuous range of versions of feature releases of the
compiler. Gaps in the range indicate incorrect features recorded for
intermediate releases.
Generally, features are made available for a particular version if the
compiler vendor documents availability of the feature with that
version. Note that sometimes partially implemented features appear to
be functional in previous releases (such as ``cxx_constexpr`` in GNU 4.6,
though availability is documented in GNU 4.7), and sometimes compiler vendors
document availability of features, though supporting infrastructure is
not available (such as ``__has_feature(cxx_generic_lambdas)`` indicating
non-availability in Clang 3.4, though it is documented as available, and
fixed in Clang 3.5). Similar cases for other compilers and versions
need to be investigated when extending CMake to support them.
When a vendor releases a new version of a known compiler which supports
a previously unsupported feature, and there are already known features for
that compiler, the feature should be listed as supported in CMake for
that version of the compiler as soon as reasonably possible.
Standard-specific/compiler-specific variables such
``CMAKE_CXX98_COMPILE_FEATURES`` are deliberately not documented. They
only exist for the compiler-specific implementation of adding the ``-std``
compile flag for compilers which need that.
Help
====
The ``Help`` directory contains CMake help manual source files.
They are written using the `reStructuredText`_ markup syntax and
processed by `Sphinx`_ to generate the CMake help manuals.
.. _`reStructuredText`: http://docutils.sourceforge.net/docs/ref/rst/introduction.html
.. _`Sphinx`: http://sphinx-doc.org
Markup Constructs
-----------------
In addition to using Sphinx to generate the CMake help manuals, we
also use a C++-implemented document processor to print documents for
the ``--help-*`` command-line help options. It supports a subset of
reStructuredText markup. When authoring or modifying documents,
please verify that the command-line help looks good in addition to the
Sphinx-generated html and man pages.
The command-line help processor supports the following constructs
defined by reStructuredText, Sphinx, and a CMake extension to Sphinx.
..
Note: This list must be kept consistent with the cmRST implementation.
CMake Domain directives
Directives defined in the `CMake Domain`_ for defining CMake
documentation objects are printed in command-line help output as
if the lines were normal paragraph text with interpretation.
CMake Domain interpreted text roles
Interpreted text roles defined in the `CMake Domain`_ for
cross-referencing CMake documentation objects are replaced by their
link text in command-line help output. Other roles are printed
literally and not processed.
``code-block`` directive
Add a literal code block without interpretation. The command-line
help processor prints the block content without the leading directive
line and with common indentation replaced by one space.
``include`` directive
Include another document source file. The command-line help
processor prints the included document inline with the referencing
document.
literal block after ``::``
A paragraph ending in ``::`` followed by a blank line treats
the following indented block as literal text without interpretation.
The command-line help processor prints the ``::`` literally and
prints the block content with common indentation replaced by one
space.
``note`` directive
Call out a side note. The command-line help processor prints the
block content as if the lines were normal paragraph text with
interpretation.
``parsed-literal`` directive
Add a literal block with markup interpretation. The command-line
help processor prints the block content without the leading
directive line and with common indentation replaced by one space.
``productionlist`` directive
Render context-free grammar productions. The command-line help
processor prints the block content as if the lines were normal
paragraph text with interpretation.
``replace`` directive
Define a ``|substitution|`` replacement.
The command-line help processor requires a substitution replacement
to be defined before it is referenced.
``|substitution|`` reference
Reference a substitution replacement previously defined by
the ``replace`` directive. The command-line help processor
performs the substitution and replaces all newlines in the
replacement text with spaces.
``toctree`` directive
Include other document sources in the Table-of-Contents
document tree. The command-line help processor prints
the referenced documents inline as part of the referencing
document.
Inline markup constructs not listed above are printed literally in the
command-line help output. We prefer to use inline markup constructs that
look correct in source form, so avoid use of \\-escapes in favor of inline
literals when possible.
Explicit markup blocks not matching directives listed above are removed from
command-line help output. Do not use them, except for plain ``..`` comments
that are removed by Sphinx too.
Note that nested indentation of blocks is not recognized by the
command-line help processor. Therefore:
* Explicit markup blocks are recognized only when not indented
inside other blocks.
* Literal blocks after paragraphs ending in ``::`` but not
at the top indentation level may consume all indented lines
following them.
Try to avoid these cases in practice.
CMake Domain
------------
CMake adds a `Sphinx Domain`_ called ``cmake``, also called the
"CMake Domain". It defines several "object" types for CMake
documentation:
``command``
A CMake language command.
``generator``
A CMake native build system generator.
See the :manual:`cmake(1)` command-line tool's ``-G`` option.
``manual``
A CMake manual page, like this :manual:`cmake-developer(7)` manual.
``module``
A CMake module.
See the :manual:`cmake-modules(7)` manual
and the :command:`include` command.
``policy``
A CMake policy.
See the :manual:`cmake-policies(7)` manual
and the :command:`cmake_policy` command.
``prop_cache, prop_dir, prop_gbl, prop_sf, prop_inst, prop_test, prop_tgt``
A CMake cache, directory, global, source file, installed file, test,
or target property, respectively. See the :manual:`cmake-properties(7)`
manual and the :command:`set_property` command.
``variable``
A CMake language variable.
See the :manual:`cmake-variables(7)` manual
and the :command:`set` command.
Documentation objects in the CMake Domain come from two sources.
First, the CMake extension to Sphinx transforms every document named
with the form ``Help/<type>/<file-name>.rst`` to a domain object with
type ``<type>``. The object name is extracted from the document title,
which is expected to be of the form::
<object-name>
-------------
and to appear at or near the top of the ``.rst`` file before any other
lines starting in a letter, digit, or ``<``. If no such title appears
literally in the ``.rst`` file, the object name is the ``<file-name>``.
If a title does appear, it is expected that ``<file-name>`` is equal
to ``<object-name>`` with any ``<`` and ``>`` characters removed.
Second, the CMake Domain provides directives to define objects inside
other documents:
.. code-block:: rst
.. command:: <command-name>
This indented block documents <command-name>.
.. variable:: <variable-name>
This indented block documents <variable-name>.
Object types for which no directive is available must be defined using
the first approach above.
.. _`Sphinx Domain`: http://sphinx-doc.org/domains.html
Cross-References
----------------
Sphinx uses reStructuredText interpreted text roles to provide
cross-reference syntax. The `CMake Domain`_ provides for each
domain object type a role of the same name to cross-reference it.
CMake Domain roles are inline markup of the forms::
:type:`name`
:type:`text <name>`
where ``type`` is the domain object type and ``name`` is the
domain object name. In the first form the link text will be
``name`` (or ``name()`` if the type is ``command``) and in
the second form the link text will be the explicit ``text``.
For example, the code:
.. code-block:: rst
* The :command:`list` command.
* The :command:`list(APPEND)` sub-command.
* The :command:`list() command <list>`.
* The :command:`list(APPEND) sub-command <list>`.
* The :variable:`CMAKE_VERSION` variable.
* The :prop_tgt:`OUTPUT_NAME_<CONFIG>` target property.
produces:
* The :command:`list` command.
* The :command:`list(APPEND)` sub-command.
* The :command:`list() command <list>`.
* The :command:`list(APPEND) sub-command <list>`.
* The :variable:`CMAKE_VERSION` variable.
* The :prop_tgt:`OUTPUT_NAME_<CONFIG>` target property.
Note that CMake Domain roles differ from Sphinx and reStructuredText
convention in that the form ``a<b>``, without a space preceding ``<``,
is interpreted as a name instead of link text with an explicit target.
This is necessary because we use ``<placeholders>`` frequently in
object names like ``OUTPUT_NAME_<CONFIG>``. The form ``a <b>``,
with a space preceding ``<``, is still interpreted as a link text
with an explicit target.
Style
-----
Style: Section Headers
^^^^^^^^^^^^^^^^^^^^^^
When marking section titles, make the section decoration line as long as
the title text. Use only a line below the title, not above. For
example:
.. code-block:: rst
Title Text
----------
Capitalize the first letter of each non-minor word in the title.
The section header underline character hierarchy is
* ``#``: Manual group (part) in the master document
* ``*``: Manual (chapter) title
* ``=``: Section within a manual
* ``-``: Subsection or `CMake Domain`_ object document title
* ``^``: Subsubsection or `CMake Domain`_ object document section
* ``"``: Paragraph or `CMake Domain`_ object document subsection
Style: Whitespace
^^^^^^^^^^^^^^^^^
Use two spaces for indentation. Use two spaces between sentences in
prose.
Style: Line Length
^^^^^^^^^^^^^^^^^^
Prefer to restrict the width of lines to 75-80 columns. This is not a
hard restriction, but writing new paragraphs wrapped at 75 columns
allows space for adding minor content without significant re-wrapping of
content.
Style: Prose
^^^^^^^^^^^^
Use American English spellings in prose.
Style: Starting Literal Blocks
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Prefer to mark the start of literal blocks with ``::`` at the end of
the preceding paragraph. In cases where the following block gets
a ``code-block`` marker, put a single ``:`` at the end of the preceding
paragraph.
Style: CMake Command Signatures
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Command signatures should be marked up as plain literal blocks, not as
cmake ``code-blocks``.
Signatures are separated from preceding content by a section header.
That is, use:
.. code-block:: rst
... preceding paragraph.
Normal Libraries
^^^^^^^^^^^^^^^^
::
add_library(<lib> ...)
This signature is used for ...
Signatures of commands should wrap optional parts with square brackets,
and should mark list of optional arguments with an ellipsis (``...``).
Elements of the signature which are specified by the user should be
specified with angle brackets, and may be referred to in prose using
``inline-literal`` syntax.
Style: Boolean Constants
^^^^^^^^^^^^^^^^^^^^^^^^
Use "``OFF``" and "``ON``" for boolean values which can be modified by
the user, such as :prop_tgt:`POSITION_INDEPENDENT_CODE`. Such properties
may be "enabled" and "disabled". Use "``True``" and "``False``" for
inherent values which can't be modified after being set, such as the
:prop_tgt:`IMPORTED` property of a build target.
Style: Inline Literals
^^^^^^^^^^^^^^^^^^^^^^
Mark up references to keywords in signatures, file names, and other
technical terms with ``inline-literal`` syntax, for example:
.. code-block:: rst
If ``WIN32`` is used with :command:`add_executable`, the
:prop_tgt:`WIN32_EXECUTABLE` target property is enabled. That command
creates the file ``<name>.exe`` on Windows.
Style: Cross-References
^^^^^^^^^^^^^^^^^^^^^^^
Mark up linkable references as links, including repeats.
An alternative, which is used by wikipedia
(`<http://en.wikipedia.org/wiki/WP:REPEATLINK>`_),
is to link to a reference only once per article. That style is not used
in CMake documentation.
Style: Referencing CMake Concepts
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
If referring to a concept which corresponds to a property, and that
concept is described in a high-level manual, prefer to link to the
manual section instead of the property. For example:
.. code-block:: rst
This command creates an :ref:`Imported Target <Imported Targets>`.
instead of:
.. code-block:: rst
This command creates an :prop_tgt:`IMPORTED` target.
The latter should be used only when referring specifically to the
property.
References to manual sections are not automatically created by creating
a section, but code such as:
.. code-block:: rst
.. _`Imported Targets`:
creates a suitable anchor. Use an anchor name which matches the name
of the corresponding section. Refer to the anchor using a
cross-reference with specified text.
Imported Targets need the ``IMPORTED`` term marked up with care in
particular because the term may refer to a command keyword
(``IMPORTED``), a target property (:prop_tgt:`IMPORTED`), or a
concept (:ref:`Imported Targets`).
Where a property, command or variable is related conceptually to others,
by for example, being related to the buildsystem description, generator
expressions or Qt, each relevant property, command or variable should
link to the primary manual, which provides high-level information. Only
particular information relating to the command should be in the
documentation of the command.
Style: Referencing CMake Domain Objects
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
When referring to `CMake Domain`_ objects such as properties, variables,
commands etc, prefer to link to the target object and follow that with
the type of object it is. For example:
.. code-block:: rst
Set the :prop_tgt:`AUTOMOC` target property to ``ON``.
Instead of
.. code-block:: rst
Set the target property :prop_tgt:`AUTOMOC` to ``ON``.
The ``policy`` directive is an exception, and the type us usually
referred to before the link:
.. code-block:: rst
If policy :prop_tgt:`CMP0022` is set to ``NEW`` the behavior is ...
However, markup self-references with ``inline-literal`` syntax.
For example, within the :command:`add_executable` command
documentation, use
.. code-block:: rst
``add_executable``
not
.. code-block:: rst
:command:`add_executable`
which is used elsewhere.
Modules
=======
The ``Modules`` directory contains CMake-language ``.cmake`` module files.
Module Documentation
--------------------
To document CMake module ``Modules/<module-name>.cmake``, modify
``Help/manual/cmake-modules.7.rst`` to reference the module in the
``toctree`` directive, in sorted order, as::
/module/<module-name>
Then add the module document file ``Help/module/<module-name>.rst``
containing just the line::
.. cmake-module:: ../../Modules/<module-name>.cmake
The ``cmake-module`` directive will scan the module file to extract
reStructuredText markup from comment blocks that start in ``.rst:``.
At the top of ``Modules/<module-name>.cmake``, begin with the following
license notice:
.. code-block:: cmake
# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.
After this notice, add a *BLANK* line. Then, add documentation using
a :ref:`Line Comment` block of the form:
.. code-block:: cmake
#.rst:
# <module-name>
# -------------
#
# <reStructuredText documentation of module>
or a :ref:`Bracket Comment` of the form:
::
#[[.rst:
<module-name>
-------------
<reStructuredText documentation of module>
#]]
Any number of ``=`` may be used in the opening and closing brackets
as long as they match. Content on the line containing the closing
bracket is excluded if and only if the line starts in ``#``.
Additional such ``.rst:`` comments may appear anywhere in the module file.
All such comments must start with ``#`` in the first column.
For example, a ``Modules/Findxxx.cmake`` module may contain:
::
# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.
#.rst:
# FindXxx
# -------
#
# This is a cool module.
# This module does really cool stuff.
# It can do even more than you think.
#
# It even needs two paragraphs to tell you about it.
# And it defines the following variables:
#
# * VAR_COOL: this is great isn't it?
# * VAR_REALLY_COOL: cool right?
<code>
#[========================================[.rst:
.. command:: xxx_do_something
This command does something for Xxx::
xxx_do_something(some arguments)
#]========================================]
macro(xxx_do_something)
<code>
endmacro()
Test the documentation formatting by running
``cmake --help-module <module-name>``, and also by enabling the
``SPHINX_HTML`` and ``SPHINX_MAN`` options to build the documentation.
Edit the comments until generated documentation looks satisfactory. To
have a .cmake file in this directory NOT show up in the modules
documentation, simply leave out the ``Help/module/<module-name>.rst``
file and the ``Help/manual/cmake-modules.7.rst`` toctree entry.
CMake upstream. It includes links to contribution instructions, which
in turn link to developer guides for CMake itself.
.. _`Find Modules`:
Find Modules
------------
============
A "find module" is a ``Modules/Find<PackageName>.cmake`` file to be loaded
A "find module" is a ``Find<PackageName>.cmake`` file to be loaded
by the :command:`find_package` command when invoked for ``<PackageName>``.
The primary task of a find module is to determine whether a package
@ -641,16 +82,11 @@ and required is up to the find module, but should be documented.
For internal implementation, it is a generally accepted convention that
variables starting with underscore are for temporary use only.
Like all modules, find modules should be properly documented. To add a
module to the CMake documentation, follow the steps in the `Module
Documentation`_ section above.
.. _`CMake Developer Standard Variable Names`:
Standard Variable Names
^^^^^^^^^^^^^^^^^^^^^^^
-----------------------
For a ``FindXxx.cmake`` module that takes the approach of setting
variables (either instead of or in addition to creating imported
@ -757,9 +193,8 @@ Make sure you comment them as deprecated, so that no-one starts using
them.
A Sample Find Module
^^^^^^^^^^^^^^^^^^^^
--------------------
We will describe how to create a simple find module for a library
``Foo``.
@ -802,8 +237,7 @@ variables and imported targets are set by the module, such as
# Foo::Foo - The Foo library
If the package provides any macros, they should be listed here, but can
be documented where they are defined. See the `Module
Documentation`_ section above for more details.
be documented where they are defined.
Now the actual libraries and so on have to be found. The code here will
obviously vary from module to module (dealing with that, after all, is the

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