From: Mathieu Bouchard <matju@...>
Date: 2006-03-28T11:50:04+09:00
Subject: Re: PATCH: A subclassable Pathname

On Tue, 28 Mar 2006, Evan Phoenix wrote:

> The reciever class is the potentially the one thats been subclassed,
> so all it's methods should attempt to convert return values into
> instances of itself.

Is there any case where you wouldn't want the return-type to be covariant 
with the receiver? Something like a #to_ordinary_pathname() would be 
obvious ;-) but there could be some subtler cases.

E.g. when I reimplemented Array#[] and such, I argued with myself quite a 
long time about whether it should return ordinary Arrays or MyArrays, and 
then, MyArray is not even a subclass of Array. In that case I decided that 
#[] should always return Array.

I think it depends on what kind of enhancements it has over the regular
PathName. Does it need be a subclass? Can you modify Pathname instead?

> I could extend Pathname and add my methods to it, but I've actually got
> 2 such classes and I don't particularly want them to share these
> methods.

Why? Cause I really don't see why.

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| Mathieu Bouchard - t�l:+1.514.383.3801 - http://artengine.ca/matju
| Freelance Digital Arts Engineer, Montr�al QC Canada