[CMake] Reusing an already built object

[Naram Qashat]

Michael Wild wrote:
> 
> On 13. Oct, 2009, at 0:13, Naram Qashat wrote:
> 
>> Say I have a main executable and a number of shared libraries that 
>> rely on that executable.  Say I have a certain C++ source that is 
>> required to be built by not only the main executable, but also every 
>> single shared library (the source in question is a Windows-specific 
>> file to handle memory allocations).  I have found that when using a 
>> Visual Studio generator, CMake causes the source file to be rebuilt 
>> for every single shared library, causing an increase in build time.  
>> Is there an easy way to have the object file not be rebuilt every 
>> single time, but be reused for all the shared libraries?  The source 
>> file is included in the main executable through add_executable(), and 
>> it's added to each of the shared libraries through add_library().
>>
>> Thanks,
>> Naram Qashat
>>
> 
> How about using a static library?
> 
> add_library( common STATIC common.c )
> add_executable( super super.c )
> target_link_libraries( super common )
> add_library( duper SHARED duper.c )
> target_link_libraries( duper common )
> 
> However, are you going to link your executable against any of the shared 
> libraries? If used in this way, you would get linking errors (unless the 
> functions in common.c are static).

I'd rather not introduce a static library for this, unless there is no other 
way.  There must be some way to reuse the object file without the use of a 
static library, I can't see this being some limitation of CMake.  But then 
again, I don't know enough about how CMake creates it's build system to know if 
there is a way or not, besides your suggestion of using a static library.

Thanks,
Naram

> Michael
>