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2038 :: importcpp problem

• geezer9 (orginal) [2016-02-13T01:04:23+01:00] view original

  Attempting to learn how to interface a nim program with a cpp module, I tried the following files:

  
  // twonum.h
  
  #ifndef twonum_H
  #define twonum_H
  
  class TwoNum {
      int a; int b;
  public:
      TwoNum(int a,int b);
      int area();
  };
  
  void* makeTwoNum(int a,int b);
  
  #endif
  Run

  
  // twonum.cxx
  #include "twonum.h"
  
  TwoNum::TwoNum(int a,int b) {
      this->a = a; this->b = b;
  }
  
  int TwoNum::area() { return  a*b; }
  
  TwoNum* makeTwoNum(int a,int b) {
      TwoNum *ob = new TwoNum(a,b);
      return ob;
  }
  Run

  
  # usetwonum.nim
  
  proc makeTwoNum(a:cint,b:cint):pointer {.nodecl,importcpp:"makeTwoNum(#,#)".}
  
  proc foo() =
      var obj = makeTwoNum(5,11)
      echo repr(obj)
  foo()
  Run

  I have tried four variations of the importcpp for makeTwoNum as follows:

  
  # 1   {.importcpp:"makeTwoNum(#,#)".}
  # 2   {.importcpp:"makeTwoNum".}
  # 3   {.cdecl,importcpp:"makeTwoNum(#,#)".}
  # 4   {.nodecl,importcpp:"makeTwoNum(#,#)".}
  Run

  Examining the resulting usetwonum.cpp file in the nimcache gave these results for the importcpp and the makeTwoNum commands:

  
  #1  N_NIMCALL(void*, makeTwoNum(#,#))(int a, int b);
  #2  N_NIMCALL(void*, makeTwoNum)(int a, int b);
  #3  N_CDECL(void*, makeTwoNum(#,#))(int a, int b);
  #4  <declaration is missing>
  
  #1  void* obj = makeTwoNum(((int) 5),((int) 11));
  #2  void* obj = ((int) 5).makeTwoNum(((int) 11));
  #3  void* obj = ((int) 5).makeTwoNum(((int) 11));
  #4  void* obj = ((int) 5).makeTwoNum(((int) 11));
  Run

  I would like to have version #2 of the NIMCALL command but #1 of the void* obj command.

  How do I do that?

  I realize there are other problems, but I cannot get past this first one.

  Thanks.

---

• gokr (orginal) [2016-02-13T14:19:08+01:00] view original

  Tweaked your code and used c2nim:

  
  gokr@yoda:~$ cat twonum.h
  // twonum.h
  
  #ifndef twonum_H
  #define twonum_H
  
  class TwoNum {
      int a; int b;
  public:
      TwoNum(int a,int b);
      int area();
  };
  
  #endif
  gokr@yoda:~$ cat twonum.cpp
  // twonum.cxx
  #include "twonum.h"
  
  TwoNum::TwoNum(int a,int b) {
      this->a = a; this->b = b;
  }
  
  int TwoNum::area() { return  a*b; }
  gokr@yoda:~$ g++ -g -c twonum.cpp
  gokr@yoda:~$ c2nim --cpp --header --out:twon.nim twonum.h
  Hint: operation successful (14 lines compiled; 0 sec total; 516.528KB; ) [SuccessX]
  gokr@yoda:~$ cat usetwonum.nim
  import twon
  
  proc foo() =
      var obj = constructTwoNum(5,11)
      echo repr(obj)
      echo $obj.area()
  
  foo()
  gokr@yoda:~$ nim cpp --cincludes:. --passL:./twonum.o usetwonum.nim
  Hint: system [Processing]
  Hint: usetwonum [Processing]
  Hint: twon [Processing]
  Hint:  [Link]
  Hint: operation successful (9927 lines compiled; 0.153 sec total; 14.143MB; Debug Build) [SuccessX]
  gokr@yoda:~$ ./usetwonum
  []
  
  55
  gokr@yoda:~$
  Run

  The resulting twon.nim looks like:

  # twonum.h
  
  type
    TwoNum* {.importcpp: "TwoNum", header: "twonum.h".} = object
  
  
  proc constructTwoNum*(a: cint; b: cint): TwoNum {.constructor, importcpp: "TwoNum(@)",
      header: "twonum.h".}
  proc area*(this: var TwoNum): cint {.importcpp: "area", header: "twonum.h".}
  
  Run

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