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