return

cmakepp_lang/utilities/return.cpp_return()

Note

This is a macro, and so does not introduce a new scope.

Syntactic sugar for returning a value from a function

CMake allows you to return variables by adding them to the parent namespace. The best way to do this is to have the caller provide the function with an identifier in which to save the result. Assume some function A called a function B, which is now returning a value x, the cpp_return function wraps the boilerplate associated with ensuring x is available in A’s namespace and also returns control back to A (i.e., any code following the cpp_return call in B will not be executed).

This works for any number of return values.

Warning

Extreme care needs to be taken when using this function in a macro as it always returns control to one scope up. Since macros do not create new scope this function will return through all macros on the stack until a function is reached. As a rule-of-thumb, never call this function from a macro.

Parameters:: *args (list[desc]) – Identifiers which needs to be set in the parent namespace.

Note

This function is a macro to avoid creating another scope. If another scope is created, then the cpp_return function could not act in the caller’s scope, i.e., the caller would still have to call set and return.

Example Usage

The following shows how to write a function which has multiple return points.

function(fxn_name return_identifier)
    set(${return_identifier} "some value")
    if(x)
        set(${return_identifier} "another value")
        cpp_return(${return_identifier})
    endif()
    cpp_return(${return_identifier})
endfunction()

The following shows how to write a function which returns multiple values:

function(fxn_name return_id_1 return_id_2)
    set("${return_id_1}" "return_value_1")
    set("${return_id_2}" "return_value_2")
    cpp_return("${return_id_1}" "${return_id_2}")
endfunction()