[CMake] parsing config.h files and setting cmake variables accordingly

[Pau Garcia i Quiles]

Hello,

I see. So, where is that config.h created? In your CMake build-system?
is it from an external library? If the former, maybe you could use
variables (cmake -DWITH_OPENGL:BOOL=1 ... ); if the latter, I don't
know (the only thing I can come with at this moment to survive
additional spaces, etc are regular expressions).

On Fri, Feb 13, 2009 at 1:10 PM, Clemens Arth <clemens.arth at gmx.at> wrote:
> Hi,
>
> thanks for the hint, but my problem is exactly the opposite of the one
> configure_file is solving. I'm already using configure_file in multiple
> places, but here I don't want to write config files, instead I want to parse
> their content back to cmake, and that's why I don't think configure_file.
>
> Regards
> Clemens
>
> Pau Garcia i Quiles wrote:
>>
>> Hello,
>>
>> Take a look at CONFIGURE_FILE
>>
>> On Fri, Feb 13, 2009 at 12:46 PM, Clemens Arth <clemens.arth at gmx.at>
>> wrote:
>>
>>>
>>> Hi,
>>>
>>> I've got a  question concerning  string processing in cmake. Our software
>>> framework consists of multiple libraries and has many different features
>>> to
>>> be enabled or disabled using #defines. For example, one option is to
>>> compile
>>> with OpenGL or with OpenGL ES support. Thus in a config.h file, one of
>>> two
>>> variables is valid to be #defined, USE_OPENGL or USE_OPENGLES. Depending
>>> on
>>> the variable defined cmake should link against a specific set of
>>> libraries.
>>>
>>> Currently determining which feature is set works the following way in my
>>> CMakeLists.txt:
>>>
>>> Code:
>>> # check for the configuration and set the corresponding GL/GLES libraries
>>> accordingly
>>> FILE(READ ${LIB_SOURCE_DIR}/include/config.h CURRENT_CONFIG)
>>> STRING(REGEX MATCH "\#define USE_OPENGLES" GLES_IS_SET ${CURRENT_CONFIG})
>>> STRING(REGEX MATCH "\#define USE_OPENGL" GL_IS_SET ${CURRENT_CONFIG})
>>> IF("#define USE_OPENGLES" STREQUAL "${GLES_IS_SET}")
>>>  MESSAGE("GLES config!")
>>> ELSE("#define USE_OPENGLES" STREQUAL "${GLES_IS_SET}")
>>>  IF("#define USE_OPENGL" STREQUAL "${GL_IS_SET}")
>>>      MESSAGE("GL config!")
>>>  ELSE("#define USE_OPENGL" STREQUAL "${GL_IS_SET}")
>>>      MESSAGE("Error! USE_GL or USE_GLES must be defined!")
>>>  ENDIF("#define USE_OPENGL" STREQUAL "${GL_IS_SET}")
>>> ENDIF("#define USE_OPENGLES" STREQUAL "${GLES_IS_SET}")
>>>
>>>
>>> Note that this is really a bad hack. First, if GLES_IS_SET is set
>>> ,GL_IS_SET
>>> is also set automatically. Second, if by accident the string does not
>>> exactly match the content (an additional <space>, or there is a second
>>> variable, for example called USE_OPENGL_EXTRAS), everything gets really
>>> weird or fails at all. Finally, a problem is that cmake does not actually
>>> notice if I changed the config.h file, so there should be an option to
>>> mark
>>> the configuration as dirty if the config.h file is altered - this is a
>>> problem which must not necessarily be solved, but maybe there is a simple
>>> solution to this.
>>>
>>> Can someone give me some tips how to improve my really ugly solution?
>>>
>>> Thanks and best regards
>>> Clemens
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>>
>>
>>
>>
>
>



-- 
Pau Garcia i Quiles
http://www.elpauer.org
(Due to my workload, I may need 10 days to answer)