CMake: GodotCPPModule.cmake

[enetheru]

After @Naros pointed out that for orchestrator the doc_source.cpp file was not being generated it made me think that a more predictable and obvious method is desirable.

Changes:

• Renamed python_callouts.cmake to GodotCPPModule.cmake
• Moved the find_package(Python3 3.4 REQUIRED) to top of GodotCPPModule.cmake to guarantee its availability.
• Added target_doc_sources CMake function

It's typical of CMake projects to APPEND to the CMAKE_MODULES_PATH to include scripts from dependencies.
Renaming the python_callouts.cmake to GodotCPPModule.cmake creates a very clear location to place any CMake functionality which is public facing.

In consumer CMakeLists.txt it would be recommended that after including the godot-cpp project to:

list(APPEND CMAKE_MODULE_PATH "${godot-cpp_SOURCE_DIR}/cmake")
include( GodotCPPModule )

To simpify the addition of documentation to a gdextension library a new function target_doc_sources has been created
which adds a dependency to generate the files on build. It also adds a new target doc_gen which will perform the doc_source.cpp generation on demand. (I can add this behind a flag, or leave it exposed by default or customise it to include the name of the target.)

This reduces the complexity of including documentation sources to a project by relieving the user of having to explicitly put the OUTPUT_PATH of the generate_doc_source function in the sources list of their target.

add_library( my_extension SHARED )

target_sources( my_extension
        PRIVATE
        src/my_source.cpp
        src/my_source.h
        src/...
)

file( GLOB_RECURSE XML_FILES_LIST LIST_DIRECTORIES NO CONFIGURE_DEPENDS
    "${CMAKE_CURRENT_SOURCE_DIR}/doc_classes/*.xml" )

target_doc_sources( my_extension ${XML_FILES_LIST} )

[dsnopek]

Thanks!

At a high-level this makes sense to me, and is definitely the sort of thing we want to get in before Godot 4.4 (since it affects the "developer interface" to the cmake config).

I just have one question about the changes...

[enetheru]

Thanks!

At a high-level this makes sense to me, and is definitely the sort of thing we want to get in before Godot 4.4 (since it affects the "developer interface" to the cmake config).

I just have one question about the changes...

I'll revert that sorry. I accidentally resolved the comment.

[dsnopek]

Thanks!