[MacRuby-devel] [MacRuby] #733: Proc as callback function for CoreAudio(AudioDeviceCreateIOProcID) isn't called

[MacRuby]

#733: Proc as callback function for CoreAudio(AudioDeviceCreateIOProcID) isn't
called
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 Reporter:  nagachika00@…          |       Owner:  lsansonetti@…        
     Type:  defect                 |      Status:  new                  
 Priority:  blocker                |   Milestone:                       
Component:  MacRuby                |    Keywords:                       
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Comment(by martinlagardette@…):

 Replying to [comment:2 nagachika00@…]:
 > Did you mean that MacRuby cannot make callback Proc Object for function
 pointer returned from last argument of AudioDeviceCreateIOProcID()?
 > [...]
 > So I think CoreAudio can call Ruby Proc object via stub callback
 function passed to second argument. Is this my misconception?

 I'm not sure I understand exactly what you're asking, so let me know if
 I'm not correctly answering:

 In its current implementation, when calling Obj-C / C methods, MacRuby
 converts ruby values (Fixnum, Strings, etc.) to C values (long, char *,
 etc.). When the needed C value is a function pointer, it will check if the
 argument is a Proc. If it is, it creates a "trampoline" function that will
 be passed to the C function, and the trampoline function simply "calls"
 (executes) the Proc.

 However, the contrary is not implemented. Aka, if a function returns a
 function pointer, or take a pointer to a function pointer, MacRuby does
 not know, yet, how to take this function pointer and make it a Ruby value
 (ideally a Proc). That is the current problem. When you pass the Pointer
 to the `AudioDeviceCreateIOProcID`, the pointer is filled with a function
 pointer. However, once the function returns, MacRuby has to translate this
 pointer to function pointer to some ruby value that can be used. And for
 now, we don't know how to do that :-).

 > If I want to distribute my MacRuby Application, can I include modified
 version of BridgeSupport file with it, and let MacRuby use it instead of
 system's one?

 You can load custom bridge support files, I guess you could do that before
 loading the framework (if I remember correctly, similar bridgesupport
 files are not loaded twice). I'll need to make sure though, but I think
 it's possible.

-- 
Ticket URL: <http://www.macruby.org/trac/ticket/733#comment:3>
MacRuby <http://macruby.org/>