function -------- Start recording a function for later invocation as a command. .. code-block:: cmake function( [ ...]) endfunction() Defines a function named ```` that takes arguments named ````, ... The ```` in the function definition are recorded; they are not executed until the function is invoked. Per legacy, the :command:`endfunction` command admits an optional ```` 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) endfunction() can be invoked through any of .. code-block:: cmake foo() Foo() 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. Arguments ^^^^^^^^^ When the function is invoked, the recorded ```` 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.