Re: [boost] CMake Modularization

Subject: Re: [boost] CMake Modularization
From: Peter Dimov (lists_at_[hidden])
Date: 2016-09-27 19:18:41

Philip Woods wrote:
> I created an example project 
> https://github.com/Elzair/cmake-boost-filesystem-test to demonstrate my 
> ideas. I added CMake build support to the minimum number of modules needed 
> to support this demo: https://github.com/Elzair/assert 
> https://github.com/Elzair/config https://github.com/Elzair/core 
> https://github.com/Elzair/filesystem/tree/master and 
> https://github.com/Elzair/system

I know next to nothing about CMake, but this doesn't seem quite the right 
way.

This:

set(BOOST_FILESYSTEM_INCLUDE_DIRS "${CMAKE_CURRENT_SOURCE_DIR}/include" 
CACHE STRING "Location of boost.filesystem headers")

should perhaps just be

target_include_directories(boost_filesystem PUBLIC 
${CMAKE_CURRENT_SOURCE_DIR}/include)

The manual dependency checking at the top:

if(NOT BOOST_CONFIG_INCLUDE_DIRS)
   message(FATAL_ERROR "Cannot find boost.config!")
endif(NOT BOOST_CONFIG_INCLUDE_DIRS)

should probably be replaced by

target_link_libraries(boost_config)

boost_config, being a header-only library, should be

add_library(boost_config INTERFACE)

The various BOOST_*_INCLUDE_DIRS and BOOST_*_LIBRARIES won't be needed; 
CMake will figure it out automatically. And the order of add_subdirectory 
will no longer matter.