Mirror of forum.nim-lang.org

9107 :: pass as parameter only a certain procedure from multiple with the same name (overloaded procs)

• veksha (orginal) [2022-04-15T02:38:48+02:00] view original

  Hello, All.

  I have this code.

  I need to pass a certain procedure (SetFocus) as parameter (LPVOID) to another procedure (pass).

  But as it turned out there are a lot of SetFocus procs in winim module. I need only one of them. Question: how can I elegantly specify the one that i need (HWND SetFocus(HWND))

  from winim as win import LPVOID
  #from winim/inc/winuser as win import nil
  
  proc pass(p: LPVOID) =
      echo p.repr
  
  #pass(win.MessageBoxA)  # this works
  pass(win.SetFocus)      # this doesn't. type mismatch. because "SetFocus" symbol is ambiguous.
  
  echo win.SetFocus.typeof  # type = None
  
  Run

  if i uncomment the second line, the code works, but i think it looks like workaround/hack.

---

• ElegantBeef (orginal) [2022-04-15T02:43:06+02:00] view original

  pass(proc(hwnd: HWND): HWND)(SetFocus))

---

• veksha (orginal) [2022-04-15T02:55:16+02:00] view original

  thanks for quick answer. unfortunately it doesn't work. (I have pasted your code as it is and imported HWND symbol.) parentheses are mismatched. doesn't compile.

---

• ElegantBeef (orginal) [2022-04-15T03:08:00+02:00] view original

  Ah sorry I've fixed it, too many parenthesis for my small brain.

---

• veksha (orginal) [2022-04-15T03:26:50+02:00] view original

  pass((proc(hwnd: HWND): HWND)(win.SetFocus))
  Run

  Error: ambiguous identifier: 'SetFocus'

---

• ElegantBeef (orginal) [2022-04-15T03:34:19+02:00] view original

  Yes this is a case of HWND describing a lot if you want a specific proc you need to do something like

  import winim
  
  proc pass(p: LPVOID) =
      echo p.repr
  
  pass (proc(hWnd: HWND): HWND{.stdcall.})(SetFocus)
  
  Run

---

• veksha (orginal) [2022-04-15T04:23:37+02:00] view original

  thanks, ElegantBeef!

  Manual: "Type conversion can also be used to disambiguate overloaded routines" this is something i have missed while learning Nim.

  this is my code now. looks fine!

  type hwndSetFocus = proc(hWnd: HWND): HWND{.stdcall.}
  pass (hwndSetFocus)(win.SetFocus)
  Run

---