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9083 :: C++ interop via Dynamic Library

• jmgomez (orginal) [2022-04-06T10:55:43+02:00] view original

  Hi guys,

  Im trying to integrate Nim into an existing C++ application via a dynamic library. I got it working via FFI

  I was wondering if it could be possible to make it work without FFI, like if the Nim dynlib were an actual C++ dynlib (which it actually is).

  If so, how the process would be? I tried to find information on it but couldn't find any. Do I need to use some special pragma? Or just marking the function with cdecl will work? Do I also need to do something else for generating the headers?

  Thanks, Juan

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• PMunch (orginal) [2022-04-06T11:14:31+02:00] view original

  This should be helpful: https://nim-lang.org/docs/manual.html#foreign-function-interface-dynlib-pragma-for-export

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• jmgomez (orginal) [2022-04-06T16:22:48+02:00] view original

  Maybe Im missing something, but I was already using dynlib and it does require the extern "C" prefix on the Cpp header which implies FFI. Im looking for something like it's shown here:

  (https://domiyanyue.medium.com/c-development-tutorial-4-static-and-dynamic-libraries-7b537656163e)

  A pure C++ library (no FFI compatible)

  Thanks!

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• sls1005 (orginal) [2022-04-07T10:44:08+02:00] view original

  I've discovered an undocumented pragma, {.exportcpp.}, that exports a proc without extern "C". But I don't think it's a good idea to use it because every C++ compiler has its own idea of name mangling , which makes your library not compatible with other compilers. That's why we need extern "C". Besides, the pragma doesn't work for dynlib, but for static lib.

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• jmgomez (orginal) [2022-04-08T20:04:46+02:00] view original

  I saw it, the problem is that it doesnt link the symbols without the extern. Im using the same compiler but I just figured that I could pass class pointers through FFI anyways so I guess Im fine with it now.

  Thanks

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