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5122 :: Winim Object Converter

• LuccaPrado (orginal) [2019-08-24T15:30:33+02:00] view original

  Hi! I'm having some doubts when trying to convert one data type to another. To be more specific, I'm trying to convert one

  seq[byte] 
  Run

  to

  ptr DATA_BLOB 
  Run

  using

  winimConverterVarObjectToPtrObject 
  Run

  But I can't figure out what I'm doing wrong... I don't understood very well how to use this converter. Already tried some things but none of them worked and I couldn't understand the example on its page. Can someone help me?

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• Stefan_Salewski (orginal) [2019-08-24T18:05:29+02:00] view original

  I'm having some doubts

  I do know nothing about winim, so maybe we should wait until its author can answer. But one hint: Looking at the source code of that converter, it is obvious that it is useless for seqs. Generally, when you have a seq, and want to pass the data to a C lib proc, you can use seq[0].addr. Maybe you have to cast it before to the right data type, like callMyCLibproc(castExpectedType])

  Reason for this notation is, that seq stores additional information like length, and seq[0] is the first element, and often one passes the address of the first element to C functions.

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• Ward (orginal) [2019-08-24T22:13:18+02:00] view original

  A lot of Windows APIs accept "pointer to some structure" as parameters, for example (in C source):

  
  MSG msg;
  GetMessage(&msg, 0, 0, 0);
  Run

  How to convert this code to nim?

  
  var msg: MSG
  GetMessage(addr msg, 0, 0, 0)
  Run

  Ok, it is easy to understand. The only problem is that I am too lazy to add "addr" before each parameter. So with that converter, I can just write:

  
  var msg: MSG
  GetMessage(msg, 0, 0, 0)
  Run

  This is the reason why the converter exists.

  Ps. Technically speaking, I add this converter is because that I want make winim be compatible with winlean.nim. In winlean, this kind of parameters often are "var parameter", but winim follow the SDK definition so they are just "ptr object". For example:

  
  # winlean
  proc getSystemTimes*(lpIdleTime, lpKernelTime, lpUserTime: var FILETIME): WINBOOL
  
  # winim
  proc GetSystemTimes*(lpIdleTime, lpKernelTime, lpUserTime: ptr FILETIME): WINBOOL
  Run

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