Re: Function as an argument

[Akiko Ogawa - RS/GIS lab]

Thank you Marcus,

I definitely like "SEL with perform:" method better. However, I may not be 
understanding how to use them correctly. I got an error when I tried.
Tell me if the following example is right:
By the way, Can M() have only (void) functions?

---- In object: EggCarton -----
// This method takes a method as arguments
- goThroughEggsWith: (SEL) methodName InObj: obj {
  for (i=0;i<cartonSize;i++) {
   id egg = [eggCartonList atOffset: i];
   [obj perform: M(methodName) with: egg];
  }
  ...
}
---- In object: EggTester ----
- compareEggTestingMethods {

  (id <EggCarton>) eggCarton;
  // Here passing methods as arguments
  [eggCarton goThroughEggsWith: M(scientificTest:) InObj: self ];  
  [eggCarton goThroughEggsWith: M(conventionalTest:) InObj: self ];
  ...
}
// Followings are the passed methods.
- scientificTest: (id) egg {
  if ([technitian xRay: egg])
     boiledEggs++;
  ...
}
- conventionalTest: (id) egg {
  if ([kid spin: egg])
     boiledEggs++;
  ...
}

>>>>>> "AO" == Akiko Ogawa <- RS/GIS lab <address@hidden>> 
writes:
>
>AO> Please advise whether a function can be passed by another function
>AO> as an argument in Objective-C.  If yes, what should the syntax be
>AO> like?
>
>Alternatively, you can pass around the SEL type that you get when you
>use M(methodName).  Call a SEL with perform:.  Functions will be somewhat
>faster.
>
>typedef void (*func_t) (int count, const char **strings);
>
>void
>print_strings (int count, const char **strings)
>{
>  int i;
>
>  printf ("count: %u\n", count);
>
>  for (i = 0; i < count; i++)
>    printf ("string[%u]: `%s'\n", i, strings[i]);
>}
>
>void
>call_func (func_t func, int count, const char **strings)
>{
>  func (count, strings);
>}
>
>int
>main (int argc, const char **argv)
>{
>  call_func (print_strings, argc, argv);
>}
>
>/*
>Local Variables:
>compile-command: "gcc callfunc.c -o callfunc"
>End:
>*/
>
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