Re: Problem overriding a factory class mehtod
Re: Problem overriding a factory class mehtod
- Subject: Re: Problem overriding a factory class mehtod
- From: Ivan Kourtev <email@hidden>
- Date: Thu, 2 Nov 2006 21:36:27 -0500
On Nov 2, 2006, at 6:59 PM, Clint Shryock wrote:
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;
}
That doesn't seem to work. The returned object is still an instance
of the superclass. Plus the app started crashing (I think -- but not
sure -- because because of the assignment to self in the class object?)
--
ivan
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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