Mirror of forum.nim-lang.org

8625 :: UFCS issue

• mantielero (orginal) [2021-11-14T18:24:19+01:00] view original

  I am having an issue with the calling convention. I have the following function:

  type
    Consumer*   = mlt_consumer
  ...
  
  proc mlt_consumer_close*(a1: mlt_consumer) {.importc, cdecl, impmltDyn.}
  ...
  proc close*(a:Consumer) =
    mlt_consumer_close(a)
  Run

  The following works:

  close(c)
  Run

  but not the following:

  c.close()
  Run

  giving me the following error:

  Error: type mismatch: got <>
  but expected one of:
  proc (a1: mlt_consumer){.cdecl.}
  Run

  Why am I having this issue?

---

• rb3 (orginal) [2021-11-15T08:56:49+01:00] view original

  Might be that impmltDyn macro is causing the a parameter to mlt_consumer_close to disappear. Try doing

  import std/macros
  
  expandMacros:
    proc mlt_consumer_close*(a1: mlt_consumer) {.importc, cdecl, impmltDyn.}
  Run

  and see what it expands to.

---

• shirleyquirk (orginal) [2021-11-15T14:03:08+01:00] view original

  If I've found the right code you've got

  type ConsumerS = object
      ...
      close: proc (a1: Consumer) {.cdecl.}
    Consumer = ptr ConsumerS
  Run

  which means c.close() refers to the member close of c, i.e. a proc which expects a parameter

---

• mantielero (orginal) [2021-11-15T17:25:33+01:00] view original

  Wow thanks a lot. I think I would have never found it.

---