Re: Compililng C++ and D together without going mad
On Wednesday, 29 April 2020 at 10:25:31 UTC, Jan Hönig wrote:
In my pet project, I am using some C++ libraries. The main
file/function is also C++. All of it successfully compiles with
cmake. Now I want to add some functionality by calling my own D
functions (which use some other modules/projects/phobos).
My questions is, what is the "proper" building tool/way.
Do I extend my CMakeFile.txt with additional instructions,
which basically do a "dmd -c ...".
Do I use dub to compile the D part as a library, and use that
in the cmake file?
Do I use dub to compile the C++ part as well?
Surely somebody has done something similar.
Can you pinpoint me to some examples? I could go from there.
For mixed language project use Cmake only, you do not need to
involve dub.
You extend Cmake to compile D files. You add these files with the
contents.
CMakeDCompiler.cmake.in:
set(CMAKE_D_COMPILER "@CMAKE_D_COMPILER@")
set(CMAKE_D_COMPILER_LOADED 1)
set(CMAKE_D_SOURCE_FILE_EXTENSIONS
@CMAKE_D_SOURCE_FILE_EXTENSIONS@)
set(CMAKE_D_OUTPUT_EXTENSION @CMAKE_D_OUTPUT_EXTENSION@)
set(CMAKE_D_COMPILER_ENV_VAR "@CMAKE_D_COMPILER_ENV_VAR@")
CMakeDetermineDCompiler.cmake:
# Find the D compiler
find_program(
CMAKE_D_COMPILER
NAMES "ldc2"
HINTS "${CMAKE_SOURCE_DIR}"
DOC "LDC compiler"
)
mark_as_advanced(CMAKE_D_COMPILER)
set(CMAKE_D_SOURCE_FILE_EXTENSIONS d)
set(CMAKE_D_OUTPUT_EXTENSION .obj)
set(CMAKE_D_COMPILER_ENV_VAR "D")
# Configure variables set in this file for fast reload later on
configure_file(${CMAKE_CURRENT_LIST_DIR}/CMakeDCompiler.cmake.in
${CMAKE_PLATFORM_INFO_DIR}/CMakeDCompiler.cmake)
CMakeDInformation.cmake:
if(NOT CMAKE_D_COMPILE_OBJECT)
set(CMAKE_D_COMPILE_OBJECT "
${CMAKE_D_FLAGS} -c --of= ")
endif()
set(CMAKE_D_INFORMATION_LOADED 1)
CMakeTestDCompiler.cmake:
# For now just do nothing in here
set(CMAKE_D_COMPILER_WORKS 1 CACHE INTERNAL "")
Put these files somewhere and tell Cmake were to find them.
set(CMAKE_MODULE_PATH "${CMAKE_MODULE_PATH}"
${THE_PATH_TO_THE_FILES}" CACHE INTERNAL "")
You need to enable D language to use it with.
enable_language(D)
You can make this more complex but this will make you start
quickly. Now Cmake will compile D files as soon as it encounters
source files with the .d extension. You can gladly mix C++ and D
files and it will link them all together.
Re: Compililng C++ and D together without going mad
On Wednesday, 29 April 2020 at 13:02:36 UTC, Jan Hönig wrote: On Wednesday, 29 April 2020 at 11:38:16 UTC, Johan wrote: LDC is a (somewhat complex) project with D and C++ code (and external C++ libraries). I think it will help you if your main() is in D (such that druntime is automatically initialized for you). https://github.com/ldc-developers/ldc -Johan Hmmm, a D main means i need to do quite some C++ bindings, with which I have 0 experience. I cannot even say if it will be possible. I will probably need: https://github.com/jupyter-xeus/xeus/blob/master/include/xeus/xkernel.hpp https://github.com/jupyter-xeus/xeus/blob/master/include/xeus/xkernel_configuration.hpp c++ stdlib's unique_ptr. And then i need to subclass a C++ class and extern this D subclass. It sounds easier to me, to manually initialize D's runtime (i imagine it being some function calls), build everything with C++, and just call D functions from C++. Manually initializing D's runtime is also possible. You need to call rt_init and rt_term: https://dlang.org/phobos/core_runtime.html#.rt_init What I meant is to - add a `int main()` in a D source file - rename your current `main` in the C++ source file to something like `the_real_main` - add a forward reference to the D file: `extern(C) int the_real_main();` - call `the_real_main` from the `main` in the D file That way you don't have to think about how to correctly initialize D's runtime. -Johan
Re: Compililng C++ and D together without going mad
On Wednesday, 29 April 2020 at 13:12:50 UTC, Johan wrote: Manually initializing D's runtime is also possible. You need to call rt_init and rt_term: https://dlang.org/phobos/core_runtime.html#.rt_init What I meant is to - add a `int main()` in a D source file - rename your current `main` in the C++ source file to something like `the_real_main` - add a forward reference to the D file: `extern(C) int the_real_main();` - call `the_real_main` from the `main` in the D file That way you don't have to think about how to correctly initialize D's runtime. -Johan I thought it was a good idea to ask in the forum! This actually helps me a lot, thanks!
Re: Compililng C++ and D together without going mad
On Wednesday, 29 April 2020 at 13:02:36 UTC, Jan Hönig wrote: I will probably need: Also this thing: https://github.com/nlohmann/json
Re: Compililng C++ and D together without going mad
On Wednesday, 29 April 2020 at 11:38:16 UTC, Johan wrote: LDC is a (somewhat complex) project with D and C++ code (and external C++ libraries). I think it will help you if your main() is in D (such that druntime is automatically initialized for you). https://github.com/ldc-developers/ldc -Johan Hmmm, a D main means i need to do quite some C++ bindings, with which I have 0 experience. I cannot even say if it will be possible. I will probably need: https://github.com/jupyter-xeus/xeus/blob/master/include/xeus/xkernel.hpp https://github.com/jupyter-xeus/xeus/blob/master/include/xeus/xkernel_configuration.hpp c++ stdlib's unique_ptr. And then i need to subclass a C++ class and extern this D subclass. It sounds easier to me, to manually initialize D's runtime (i imagine it being some function calls), build everything with C++, and just call D functions from C++. Or do you think it is worth the hassle with bindings? I have done C++ bindings once,years ago in python and it was a not pleasent.
Re: Compililng C++ and D together without going mad
On Wednesday, 29 April 2020 at 10:25:31 UTC, Jan Hönig wrote: In my pet project, I am using some C++ libraries. The main file/function is also C++. All of it successfully compiles with cmake. Now I want to add some functionality by calling my own D functions (which use some other modules/projects/phobos). My questions is, what is the "proper" building tool/way. Do I extend my CMakeFile.txt with additional instructions, which basically do a "dmd -c ...". Do I use dub to compile the D part as a library, and use that in the cmake file? Do I use dub to compile the C++ part as well? Surely somebody has done something similar. Can you pinpoint me to some examples? I could go from there. LDC is a (somewhat complex) project with D and C++ code (and external C++ libraries). I think it will help you if your main() is in D (such that druntime is automatically initialized for you). https://github.com/ldc-developers/ldc -Johan
