[CMake] coding style for modules

[Don Hinton]

I normally see it like this:

if( CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR )
  project(foo)
# ...
endif()

hth...
don

On Wed, Jan 3, 2018 at 6:09 PM, Dave Milter <davemilter at gmail.com> wrote:

> Hello,
>
> If there is some libfoo that I want to use in my project,
> and this libfoo has it's own CMakeLists.txt I have 3 options to deal
> with such external dependency:
>
> a) Treat it like every other external dependency and write cmake code
>   like FindLibFoo.cmake to find libfoo on file system.
>
> b)Include this project as git submodule and use ExternalProject to
> invoke `cmake` and `cmake --build`
>
> c)Include this project as git submodule and use add_subdirectory(libfoo)
>
>
> Variant "c" has advantages that potentially in this case it is
> possible to have almost the same compiler flags for libfoo and main
> project, which may give the most
> robust solution in case of usage visual studio (release/debug/multi
> thread/single thread CRT problems), plus it is simplify a lot cross
> compilation.
>
> But usually "libfoo" CMakeLists.txt looks like this:
>
> ```
> cmake_minimum_required(VERSION 3.10)
>
> #configure many things that important for standalone
> #project, but not requires for project as part of another project
> #for example in case of gcc we add some special flags like -Wall
> -Wextra -pedantic and so on
>
> add_library(foo SHARED sources)
> ```
>
> and part between `cmake_minimum_required` and `add_library` is useless
> and sometime prevent cross compilation and usage of the same compiler
> flags.
>
> So question how should I organize CMakeListst.txt of libfoo help deals
> with "c"?
>
> Should I move all specific for standalone project code to:
>
> if(CMAKE_SOURCE_DIR STREQUAL PROJECT_SOURCE_DIR)
> # i am standalone
> endif()
>
> or may be I should use some other tricks?
> --
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