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83 lines
2.4 KiB
ReStructuredText
83 lines
2.4 KiB
ReStructuredText
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function
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--------
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Start recording a function for later invocation as a command.
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.. code-block:: cmake
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function(<name> [<arg1> ...])
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<commands>
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endfunction()
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Defines a function named ``<name>`` that takes arguments named
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``<arg1>``, ... The ``<commands>`` in the function definition
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are recorded; they are not executed until the function is invoked.
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Per legacy, the :command:`endfunction` command admits an optional
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``<name>`` argument. If used, it must be a verbatim repeat of the
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argument of the opening ``function`` command.
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A function opens a new scope: see :command:`set(var PARENT_SCOPE)` for
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details.
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See the :command:`cmake_policy()` command documentation for the behavior
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of policies inside functions.
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See the :command:`macro()` command documentation for differences
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between CMake functions and macros.
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Invocation
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^^^^^^^^^^
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The function invocation is case-insensitive. A function defined as
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.. code-block:: cmake
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function(foo)
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<commands>
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endfunction()
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can be invoked through any of
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.. code-block:: cmake
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foo()
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Foo()
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FOO()
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cmake_language(CALL foo)
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and so on. However, it is strongly recommended to stay with the
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case chosen in the function definition. Typically functions use
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all-lowercase names.
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.. versionadded:: 3.18
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The :command:`cmake_language(CALL ...)` command can also be used to
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invoke the function.
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Arguments
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^^^^^^^^^
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When the function is invoked, the recorded ``<commands>`` are first
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modified by replacing formal parameters (``${arg1}``, ...) with the
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arguments passed, and then invoked as normal commands.
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In addition to referencing the formal parameters you can reference the
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``ARGC`` variable which will be set to the number of arguments passed
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into the function as well as ``ARGV0``, ``ARGV1``, ``ARGV2``, ... which
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will have the actual values of the arguments passed in. This facilitates
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creating functions with optional arguments.
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Furthermore, ``ARGV`` holds the list of all arguments given to the
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function and ``ARGN`` holds the list of arguments past the last expected
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argument. Referencing to ``ARGV#`` arguments beyond ``ARGC`` have
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undefined behavior. Checking that ``ARGC`` is greater than ``#`` is
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the only way to ensure that ``ARGV#`` was passed to the function as an
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extra argument.
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See Also
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^^^^^^^^
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* :command:`cmake_parse_arguments`
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* :command:`endfunction`
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* :command:`return`
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