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8434 :: Can I somehow share a C++ class with Nim, either by reading it from a dll or otherwise?

• Solaris (orginal) [2021-09-17T10:33:09+02:00] view original

  I am completely new at the Nim language so pardon my ignorance. I tried to google this and search through docs, but I didn't see anything definitive. I saw a post related to this but it was from 2014 and thought maybe something has changed since then. In my particular case I have a simple class (no templates, macros, virtuals or anything particularly special) that I want to use in both C++ and Nim. I could re-create the class as an Object in Nim but then making changes to it in Nim won't reflect in C++ and vice-versa.

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• jyapayne (orginal) [2021-09-17T15:05:31+02:00] view original

  See my answer to this thread: https://forum.nim-lang.org/t/8429

  You can also see here for the section in the manual.

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• Solaris (orginal) [2021-09-18T06:15:35+02:00] view original

  The problem with that kind of solution is that it looks like I would have to locally do some of the class implementation. If the cpp class changes, I'd have to update the local version as well. Keeping these classes in-sync can become difficult as projects grow. I could flip it around and drive the cpp class from the Nim class. If I have a class definition with some functionality in Nim, I can probably use compileToCpp to get it to the Cpp project. Any issues with this?

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• Araq (orginal) [2021-09-18T06:56:45+02:00] view original

  If the cpp class changes, I'd have to update the local version as well.

  But if you use c2nim you can run c2nim again should the cpp class change.

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• rforcen (orginal) [2021-09-18T10:36:15+02:00] view original

  this may help:

  
  # cpp integration
  # compile w/
  # nim cpp -r cpp01.nim
  
  
  {.emit: """
  class Foo {
    public:
      int i,j,k;
  };
  """.}
  
  type Foo {.importcpp: "class Foo", nodecl.} = object
    i:cint
    j:cint
    k:cint
  
  proc `$`(f:Foo):string="Foo(i:" & $f.i & ", j:" & $f.j & ", k:" & $f.k & ")"
  var foo:Foo
  
  echo foo
  Run

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