[Cmake] [PATCH] Custom LIB/EXE output path for each CMakeList.txt

[Nitin Gupta]

Hi Bill,
	The solution does not seems to work for
	Linux builds, mainly when an executable in 
	higher CMakeLists.txt *depends* upon the
	library in one of SUBDIRs. In this case
	the Makefile of higher directory (executable)
	assumes the SUBDIR library in the path
	defined by its LIBRARY_OUTPUT_PATH whereas
	the Makefile of SUBDIR library contains the rules
	that assumes the library to be generated in 
	directory defined by its LIBRARY_OUTOUT_PATH.
	The "make" would break when building DEPEND_LIBs
	of executable.
	Consider:

 PROJECT(foo)
 SET(FOO_EXE_PATH "foo_exe" CACHE...)
 SET(FOO_EXE_PATH "foo_lib" CACHE...)
 SET(EXECUTABLE_OUTPUT_PATH ${FOO_EXE_PATH})
 SET(LIBRARY_OUTPUT_PATH ${FOO_LIB_PATH}) 
 
 SUBDIR(BAR1 BAR2)
 ADD_EXECUTABLE(foo ...)
 ADD_DEPENDENCIES(foo bar1 bar2)
 
 
 ---BAR1---
 PROJECT(BAR1)
 SET(BAR1_LIB_PATH "bar1_lib" CACHE...)
 SET(EXECUTABLE_OUTPUT_PATH ${BAR_EXE_PATH})
 
 ADD_LIBRARY(bar1 ...) 

 ---BAR2---
 PROJECT(BAR2)
 SET(BAR2_LIB_PATH "bar2_lib" CACHE...)
 SET(EXECUTABLE_OUTPUT_PATH ${BAR_EXE_PATH})

 ADD_LIBRARY(bar2 ...) 
	
Now the makefile of FOO would contain
	foo_DEPEND_LIBS = ... lib/libbar1.a lib/libbar2.a
	...
	lib/libbar1.a :...
		cd BAR1;..; make lib/libbar1.a

	Whereas the Makefile in BAR1 would contain target
	bar1_lib/libbar1.a instead.

	Hence a "make" for FOO would break complaining
	**No rule to make target lib/libbar1.a

> 
> There is no need for a patch.  This can already be done from the 
> CMakeLists.txt files
> with a SET command.   A common technique for overriding global 
> cache variables is
> to create a project specific variable, and then to use SET to 
> override the global
> one in the local directory.
> 
> 
> So, the following is an example:
> 
> PROJECT(foo)
> SET(FOO_EXE_PATH CACHE...)
> SET(EXECUTABLE_OUTPUT_PATH ${FOO_EXE_PATH})
> 
> 
> SUBDIR(BAR)
> 
> 
> ---BAR---
> PROJECT(BAR)
> SET(BAR_EXE_PATH CACHE...)
> SET(EXECUTABLE_OUTPUT_PATH ${BAR_EXE_PATH})
> 


> 
> EXECUTABLE_OUTPUT_PATH and LIBRARY_OUTPUT_PATH should remain global,
> as many times you really do want one directory for a combined project.
> For example ParaViewComplete which is a combination of VTK and ParaView
> needs to have one.   The main reason for wanting one directory is so
> that dll builds on windows can run without having to set the PATH.
> There is no rpath on windows, however exes will look in the 
> current directory
> for dll's.
> 

The patch should not hurt such scenarios. In fact anything that is 
already working should keep on working in the same manner.

Thanks and Regards,
Nitin

> -Bill
> 
>