Back To Basics: CMake Functions and Macros

CMake supports both functions and macros to provide a named abstraction for some repetitive works. A function or macro always define a new command.

Functions

function(<someName> [<arg1> ...])
  <commands>
endfunction()

where name is the name of the function, with arguments arg1, arg2, etc.

Example

I am foo!! 
I am foo!! 
I am foo!!
I am foo!

Here the function name is case-insensitive. You can call in any case, but it’s always recommended to use the same name declared in the function definition.

Function Arguments

A cmake function can take two types of arguments.

• named or keyword arguments
• optional arguments

Named arguments are mandatory and will throw error if not provided. You don’t need a comma between argument names.

Output

Address: germany munich

Optional arguments can be accessed using some predefined variables.

ARGC : Total number of arguments(named arguments + optional arguments)

ARGV : list of variables containing both named and optional arguments

ARGN : list of variables containing only optional arguments

Other than those three variables, CMake also provides ARGV0, ARGV1, ARGV2, … which will have the actual values of the arguments passed in. Referencing to ARGV# arguments beyond ARGC will have undefined behavior.