[CMake] Defining a function in a macro

[David Cole]

Ouch... my brain hurts...

Another idea would be to write the "generated functions" out to a file, 
and then, after all functions are written to the file, include the file.

Might result in something you can actually look at in an editor (and 
make sense of) without your brain hurting too much, too.

;-)

D


-----Original Message-----
From: Walter Gray <chrysalisx at gmail.com>
To: cmake <cmake at cmake.org>
Sent: Fri, Aug 1, 2014 8:32 pm
Subject: [CMake] Defining a function in a macro


Hey List -
Just wanted to put this out there for posterity, and in case anyone 
runs
into the same question I had.  I had a bunch of nearly identical
functions, so I wanted to write a function to define them for me to
reduce code repetition.  The problem I ran into was that if you write

macro(_define_function name)
   function(namespaced_${function_name} ...)
       message(${ARGV} from ${name})
   endfunction()
endmacro()

_define_function(foo)
namespaced_foo("Message")

you actually wind up printing "foo from foo", since all variable
references to a macro are expanded first.  I also couldn't use a
function, since there would be no way to access ${name} from inside the
function (that I'm aware of - please correct me on this if I'm wrong)

The solution I came up with was, if I wanted to reference the 
function's
argv, I would do a double-dereference of a string containing "ARGV" 
like so:

macro(_define_function name)
   function(namespaced_${function_name} ...)
       set(my_argv ARGV)
       message(${${my_argv}} from ${name})
   endfunction()
endmacro()

This produced the correct results.  If any of you know of a cleaner way
to do this, I'd love to hear about it.  If not, have fun writing
functions to write your functions!

As a relatively useless, but I thought entertaining aside:

macro(_define_function name my_argv)
   function(namespaced_${function_name} ...)
       message(${my_argv} from ${name})
   endfunction()
endmacro()
_define_function(foo "\${ARGV}")
namespaced_foo("Message")

The result is "foo Message from foo" because ${my_argv} gets expand to
${ARGV}, which then expands to "foo ${ARGV}".

Thanks!
--

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