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7535 :: How to declare function pointer type ?

• kcvinu (orginal) [2021-02-19T13:58:10+01:00] view original

  Hi all, I saw this code in SO to declare a function pointer.

  
  (int -> int)
  Run

  But how do i declare a function pointer of a function with no return type and more than one parameter ? Thanks in advance.

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• Clonk (orginal) [2021-02-19T14:02:34+01:00] view original

  Hi,

  proc are already pointer in Nim so it's as easy as a cast :

  var fPtr : pointer = getFunctionPointer() # How you get your function pointer may vary
  var myproc : (proc(arg: int) {.cdecl, gcsafe.}) = cast[(proc(arg: int) {.cdecl, gcsafe.})](fPtr)
  myproc(3)
  Run

  There is more example here : https://nim-lang.org/docs/dynlib.html#examples-loading-a-simple-c-function.

  Note that stdcall pragma is windows specific and should be replaced by cdecl on Linux.

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• SolitudeSF (orginal) [2021-02-19T14:03:19+01:00] view original

  arrow syntax is just a sugar. https://nim-lang.org/docs/sugar.html#-%3E.m%2Cuntyped%2Cuntyped

  type P = proc(a: int): int
  Run

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• kcvinu (orginal) [2021-02-19T14:45:31+01:00] view original

  @Clonk, Thanks.

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• kcvinu (orginal) [2021-02-19T14:48:33+01:00] view original

  @SolitudeSF Yes, that's what i wanted.

  
  type
      fnPtr = (int, int)
  Run

  I want something like this. A function with 2 int params and no return value.

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• shirleyquirk (orginal) [2021-02-19T15:28:28+01:00] view original

  var fnPtr1: proc(a: int, b: int) #or import sugar var fnPtr2: (int,int) -> void

  Run

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• kcvinu (orginal) [2021-02-19T15:48:17+01:00] view original

  Hi shirleyquirk Thanks for the answer. :)

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