From: dblack@...
Date: 2007-02-17T03:53:42+09:00
Subject: Re: Oppinions on RCR for dup on immutable classes

Hi --

On Sat, 17 Feb 2007, Phrogz wrote:

> From: SonOfLilit [mailto:sonoflilit@gmail.com]
> Sent: Friday, February 16, 2007 10:48 AM
>> Ruby is always about principle-of-least-surprise and this behavior
>> really surprised me when I first read about it non-list (I've stayed
>> away from object copies in MY code, because it all seems so hacky and
>> arcane to me... Truns out it was a good idea)
>
> Actually, Ruby is about the principle-of-least-surprise-for-matz.
>
> I used to think POLS applied to everyone when I started with Ruby.
> Many people, including Matz, pointed out that it's impossible to make
> things unsurprising to everyone, because people will be surprised by
> different things.
>
> Just because something is surprising to you doesn't mean that it
> should be changed in Ruby. You are advised (as was I) not to use POLS
> as justification for why something should be changed.
>
> ...
>
> Having said that, I personally would prefer for 3.dup to 'just work',
> returning an object that is equivalent to the original. Just because
> the new instance happens to be the same doesn't mean that it's bad -
> as an immutable object, the only way to tell is via object_id, anyhow.

It doesn't mean it's bad, but it does mean that it isn't a duplicate
:-)  At least, I wouldn't think that dup is the right name for a
method that might actually return the receiver.


David

-- 
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