Re: Strange problem when not declaring the functions in interface

FROM : Ivan S. Kourtev
DATE : Mon Apr 18 23:16:31 2005

As far as I understand it, the runtime can tell whether an object 
responds to a particular message before sending the message to the 
object.  But the runtime doesn't match the return type (or check the 
type) against what you expect it to be (not to mention it would be 
probably hard to tell what you expect).

--
ivan

On Apr 18, 2005, at 5:06 PM, Pradeep Kumar wrote:

>
>  BTW, you work around works fine. But it still doesn't explain why is 
> it assuming that values
>  are id. Isn't it supposed to be decided during run time?
>
>  Thanks
>  prady
>
>
>  On Tue, 19 Apr 2005 Ivan S.Kourtev wrote :
>  >The default return type is (id).  If you don't declare the functions 
> you should do:
>  >
>  >i = i + (int)[self foo1];
>  >
>  >--
>  >ivan
>  >
>  >On Apr 18, 2005, at 4:08 PM, Pradeep Kumar wrote:
>  >
>  >>  Hi All
>  >>
>  >>  I am not sure if I am missing something really fundamental or it 
> is really a bug. But I
>  have
>  >>  this strange problem that's occurring when functions are not 
> declared in the interface.
>  >>  Thought of broadcasting this incase some one has any insight on 
> why this is
>  happening.
>  >>
>  >>  Please review the following code snippet. Assume that the 
> functions foo1 and foo2 are
>  >>  declared in the interface declaration of MyObject.
>  >>
>  >>  @implementation MyObject
>  >>
>  >>  -(void)awakeFromNib
>  >>  {
>  >>       NSLog(@"[self foo1] returned %d", [self foo1]);
>  >>       NSLog(@"[self foo2] returned %d", [self foo2]);
>  >>       int foo1 = [self foo1];
>  >>       int foo2 = [self foo2];
>  >>       NSLog(@"Variables foo1 = %d\tfoo2 = %d", foo1, foo2);
>  >>             int i = 100;
>  >>       NSLog(@"i = %d", i);
>  >>             i = i+[self foo1];
>  >>       NSLog(@"Executing i = i+[self foo1] = %d", i);
>  >>       i = i+[self foo2];
>  >>       NSLog(@"Executing i = i+[self foo2]; = %d", i);
>  >>  }
>  >>
>  >>  -(int)foo1
>  >>  {
>  >>       return 10;
>  >>  }
>  >>
>  >>  -(int)foo2
>  >>  {
>  >>       return 20;
>  >>  }
>  >>
>  >>  @end
>  >>
>  >>  The result you get in the log is
>  >>
>  >>  [self foo1] returned 10
>  >>  [self foo2] returned 20
>  >>  Variables foo1 = 10     foo2 = 20
>  >>  i = 100
>  >>  Executing i = i+[self foo1] = 110
>  >>  Executing i = i+[self foo2]; = 130
>  >>
>  >>  The results are perfect.
>  >>
>  >>  Now remove the declarations of foo1 and foo2 from the interface 
> file of MyObject. After
>  >>  doing this here's what I get.
>  >>
>  >>  [self foo1] returned 10
>  >>  [self foo2] returned 20
>  >>  Variables foo1 = 10     foo2 = 20
>  >>  i = 100
>  >>  Executing i = i+[self foo1] = 410
>  >>  Executing i = i+[self foo2]; = 1660
>  >>
>  >>  See the results of the last two statements. 410 and 1660. Why is 
> this happening?
>  >>
>  >>  I am using XCode 1.5 with  Component versions Xcode IDE: 389.0, 
> Xcode Core: 387.0,
>  >>  ToolSupport: 372.0 on 10.3.9 (7W98). I know it is recommended 
> that functions be
>  declared
>  >>  in the interface. But can not declaring the functions cause such 
> a huge difference in
>  ways
>  >>  you can use non-declared functions?
>  >>
>  >>  Thanks
>  >>  prady
>  >>
>  >>
>  >>
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>  --
>  prady
>
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