[CMake] MACRO arguments

[Brad King]

Filipe Sousa wrote:
> The fallowing code is making me crazy. I can't understand why the output is 
> always FALSE
> 
> MACRO(FOO1 x)
>   IF(x)

This is the same as writing

   IF(x)

outside the macro.

> MACRO(FOO2 x)
>   IF(${x})

This is the same as writing

   IF(hello)

outside the macro.

> MACRO(FOO3 x)
>   IF("${x}")

This is the same as writing

   IF("hello")

outside the macro.

Macro arguments are replaed by doing a string replacement of ${x} with 
the value of the argument.  They are NOT variables, which is why these 
are called macros and not procedures or functions.  You can convert 
macro arguments to variables using the SET command:

MACRO(FOO4 x)
   SET(X "${x}")
   IF(X)
     MESSAGE(TRUE)
   ELSE(X)
     MESSAGE(FALSE)
   ENDIF(X)
ENDMACRO(FOO4)

-Brad