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Re: Problem overriding a factory class mehtod
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Re: Problem overriding a factory class mehtod


  • Subject: Re: Problem overriding a factory class mehtod
  • From: "Clint Shryock" <email@hidden>
  • Date: Thu, 2 Nov 2006 17:59:48 -0600

you're FooB method only returns the result of the call to the super's
method, which returns a FooA object.  you never set any FooB variables...

if you would like a FooB object and still use the superclass's code, expand
your (FooB*)fooWithInt:(int)x method to set those specific FooB variables

+ (FooB*)fooWithInt:(int)x {
 self = [super fooWithInt:x];
 [self setFooBVariable1...];
 [self setFooBVariables...];
 return self;
}

On 11/2/06, Ivan Kourtev <email@hidden> wrote:

I am faced with the following situation involving inheritance:

Class FooB inherits from class FooA.  Class FooA implements a class
method

+ (FooA*)fooWithInt:(int)x;

The problem seems to arise with calls such as [FooB fooWithInt:x].

If I don't implement + [FooB fooWithInt], then I just get back a FooA
object (doesn't have FooB's variables).

If I override

+ (FooB*)fooWithInt:(int)x {
   return [super fooWithInt:x];
}

then I get back a FooA object again.

So what is the "by-the-book" correct way to handle such situations?
I suppose a full reimplementation of + [FooB fooWithInt] (one that
doesn't call [super ...]) would do but then I am not able to reuse
the superclass's code.  Not a problem in my case (I own all classes)
but what if I were working with another party's library and a header
file?

-- ivan
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  • Follow-Ups:
    • Re: Problem overriding a factory class mehtod
      • From: Ivan Kourtev <email@hidden>
References: 
 >Problem overriding a factory class mehtod (From: Ivan Kourtev <email@hidden>)

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