Basic OBS Studio plugin, written in nim, supporting C++ (C fine too)

obsplugin.nim

# nim cpp --app:lib .\obsplugin.nim

import nimline

cppincludes("obs-studio/libobs")

defineCppType(ObsData, "obs_data_t" , "obs-module.h")
defineCppType(ObsModule, "obs_module_t" , "obs-module.h")
defineCppType(ObsSource, "obs_source_t" , "obs-module.h")
defineCppType(ObsSourceInfo, "struct obs_source_info" , "obs-module.h")

type
  ObsPlugin = object

proc obsplugin_create(data: ptr ObsData; source: ptr ObsSource): pointer {.cdecl, exportc, dynlib.} =
  result = cast[ptr ObsPlugin](alloc0(sizeof ObsPlugin))

proc obsplugin_destroy(data: pointer) {.cdecl, exportc, dynlib.} =
  dealloc(data)

proc obsplugin_get_name(_: pointer): cstring {.cdecl, exportc, dynlib.} =
  result = "ObsPlugin".cstring

## OBS_DECLARE_MODULE()
var obsModulePointer: ptr ObsModule
proc obs_module_set_pointer(module: ptr ObsModule) {.cdecl, exportc, dynlib.} =
  obsModulePointer = module

proc obs_current_module(): ptr ObsModule {.cdecl, exportc, dynlib.} = obsModulePointer

proc obs_module_ver(): uint32 {.cdecl, exportc, dynlib.} = global.LIBOBS_API_VER.to(uint32)
##

## Loader + Struct
proc obsRegisterPlugin(info: ptr ObsSourceInfo; size: csize) {.cdecl, dynlib: "obs.dll", importc: "obs_register_source_s".}
var obsplugin_info {.importc, nodecl.}: ObsSourceInfo # must be outside the proc or nim comiler fails
proc obs_module_load(): bool {.cdecl, exportc, dynlib.} =
  {.emit: """struct obs_source_info obsplugin_info = { 0 };
  obsplugin_info.id           = "obsplugin";
  obsplugin_info.type         = OBS_SOURCE_TYPE_INPUT;
  obsplugin_info.output_flags = 0;
  obsplugin_info.get_name     = obsplugin_get_name;
  obsplugin_info.create       = obsplugin_create;
  obsplugin_info.destroy      = obsplugin_destroy;
  """.}
  obsRegisterPlugin(addr obsplugin_info, sizeof(ObsSourceInfo))
  return true
##