From: Bojan Mihelac <lists@...>
Date: 2006-06-18T05:09:17+09:00
Subject: Re: Overiding method in String

Matthew Smillie wrote:
> On Jun 17, 2006, at 20:48, Bojan Mihelac wrote:
> 
>> Do I do something wrong here or I cannot override method upcase in 
>> String?
>>
>> class String
>>   def upcase
>>     super.upcase
>>   end
>> end
>>
>> "abc".upcase
> 
> That's not overriding the method, but redefining it.  Overriding takes 
> place in subclasses, and you can definitely override the method 
> (below).  You'll also note that super doesn't work quite the same way as 
> it does in Java - it's not a reference to the superclass, it calls the 
> overridden method directly; also, the superclass of String is Object, 
> which doesn't have an upcase method, so you would have had problems 
> there as well.
> 
> class StringLikeThing < String
>   def upcase
>     super
>   end
> end
> 
> str = StringLikeThing.new("foo")
> => "foo"
> str.upcase
> => "FOO"
> 
> You can also redefine the method, if that really is what you're after.
> 
> class String
>   def upcase
>     "This used to be the upcase method, now it's gone!"
>   end
> end
> "abc".upcase
> => "This used to be the upcase method, now it's gone!"
> 
> If you still want to use the old behaviour, but with some modification, 
> you can use an alias:
> 
> class String
>   alias :real_upcase :upcase
>   def upcase
>     "upcase: " + real_upcase
>   end
> end
> "abc".upcase
> => "upcase: ABC"
> 
> Hope that helps.
> matthew smillie
> 
> 
> 
> 

Thanks for both quick answers, it's all clear now. I used aliasing to 
redefine module methods.

best regards,
Bojan Mihelac

-- 
Bojan Mihelac
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