[CMake] How to use DEFINE_SYMBOL properly?

[Mike Jackson]

Just to get some more clarification, what exactly do you mean by "...this
 visibility macro turns out to be always the same thing in every
 project...,"

The only thing you can say for certain is that for the versions of
Visual Studio and GCC _currently_ released the macros seem to stay the
same. There is absolutely NO guarantee that Microsoft, Apple, GNU or
someone else will NOT change that in the future.

 So right now the code that needs to be included in your project via a
header file is pretty much "boilerplate" code and is simple and
straight forward to insert into your project.

 Also, if you are converting another non-cmake project to CMake then
how that projects goes about implementing their visibility macros may
be different than how CMake chose to do it.
_________________________________________________________
Mike Jackson                  mike.jackson at bluequartz.net

On Tue, Feb 9, 2010 at 8:59 AM, Hilton Medeiros
<medeiros.hilton at gmail.com> wrote:
> Thanks a lot for the answers.
>
> Indeed, I already knew this macro, but I thought that since this
> visibility macro turns out to be always the same thing in every
> project, CMake would have it built in. I can't see why this is not the
> case yet.
>
> Well, back to #defines...
>
> Thanks again,
> Hilton
>
> On Tue, 9 Feb 2010 08:29:36 -0500
> Mike Jackson <mike.jackson at bluequartz.net> wrote:
>
>> http://www.cmake.org/Wiki/BuildingWinDLL
>>
>> _________________________________________________________
>> Mike Jackson                  mike.jackson at bluequartz.net
>> BlueQuartz Software                    www.bluequartz.net
>> Principal Software Engineer                  Dayton, Ohio
>>
>>
>>
>> On Tue, Feb 9, 2010 at 8:25 AM, Pau Garcia i Quiles
>> <pgquiles at elpauer.org> wrote:
>> > Hello,
>> >
>> > You are doing it wrong. You need to create a header file
>> > (myproject_exports.h, for instance) following
>> > http://gcc.gnu.org/wiki/Visibility . If you call your visibility
>> > macro target_EXPORTS, you do not need to modify the value of
>> > DEFINE_SYMBOL at all, CMake will automagically make use of it. You
>> > only need to do set_target_properties( target PROPERTIES
>> > DEFINE_SYMBOL my_visibility_macro ) if you want to use a different
>> > name for the macro (usually because it is an already-existing
>> > project which you are converting to CMake).
>> >
>> > On Tue, Feb 9, 2010 at 1:25 PM, Hilton Medeiros
>> > <medeiros.hilton at gmail.com> wrote:
>> >> Hello,
>> >>
>> >> From what I read and understood this DEFINE_SYMBOL property should
>> >> be defined like this (or something like this):
>> >>
>> >> On Windows, as shared library: target_EXPORTS=__declspec(dllexport)
>> >> On Linux, as shared library:
>> >> target_EXPORTS=__attribute__((visibility("default")))
>> >>
>> >>
>> >> So that I can use this symbol like this:
>> >>
>> >> class target_EXPORTS ExampleClass {...};
>> >>
>> >>
>> >> But on my machine (Linux, gcc) while building a shared library,
>> >> with CMake 2.8.0, I'm getting the error below because CMake is
>> >> defining this property with -Dtarget_EXPORTS=0:
>> >>
>> >> error: expected identifier before numeric constant
>> >>
>> >> What am I missing?
>> >>
>> >> Kind regards,
>> >> Hilton
>> >> _______________________________________________
>> >> Powered by www.kitware.com
>> >>
>> >> Visit other Kitware open-source projects at
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>> >>
>> >> Please keep messages on-topic and check the CMake FAQ at:
>> >> http://www.cmake.org/Wiki/CMake_FAQ
>> >>
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>> >>
>> >
>> >
>> >
>> > --
>> > Pau Garcia i Quiles
>> > http://www.elpauer.org
>> > (Due to my workload, I may need 10 days to answer)
>> > _______________________________________________
>> > Powered by www.kitware.com
>> >
>> > Visit other Kitware open-source projects at
>> > http://www.kitware.com/opensource/opensource.html
>> >
>> > Please keep messages on-topic and check the CMake FAQ at:
>> > http://www.cmake.org/Wiki/CMake_FAQ
>> >
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>> >
>
>