[Cmake] Adding a debug switch with CMake

[Neil Killeen]

I'd like my system to be so that I can build
with the debugger if need be.

Ideally, I'd like to be able to turn the debugger on
for selected code only.

With CMake, it seems to me that I have to turn it
on for everything.  Thus, in CMakeLists.txt I have
at present

# Debug ?
OPTION (DEBUG "Turn on the debugging compiler options ?" OFF)

IF (DEBUG)
  SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O0 -g")
ENDIF (DEBUG)



this means the user must rerun cmake and regenerate the
Makefiles which will enable global debugging.

I'd prefer it if I could have the user issue the command

% make debug

and for that directory the debugger is turned on.

Is it possible to configure CMake to have a 'debug'
target in this way ?

thanks
Neil