From: Kevin Ballard <kballard@...>
Date: 2005-10-18T22:41:58+09:00
Subject: Re: A couple of questions/statements from a Ruby neohacker


Robert Klemme wrote:
> Christophe Grandsire wrote:
> > I believe the convention that bang methods always have a non-bang
> > alternative, and that destructive methods without a non-destructive
> > alternative don't have one, is pretty well followed.
>
> Anomalies I can think of off the top of my head:
>
>  - Hash#update and Hash#merge: those do the same but #merge creates a new
> instance while #update doesn't.

You do know that there exists a Hash#merge! as well, which Hash#update
is an alias of, yes? I don't find this an anomaly. The name #update to
me implies that the existing hash will be updated with the new keys,
while #merge implies the two hashes will be merged to form a new one.
And that's exactly what happens.

>  - Even for Array#delete it would make sense to have two variants - one
> that returns a copy with selected elements removed and another one that
> modifies in place.

Except Array#delete returns the deleted element, so if you turned it
into Array#delete! and added a new non-destructive Array#delete, then
you'd have to change the return value, and the method would now be a
completely different method. After all, an Array#delete that's
non-destructive and returns the deleted element would be completely
useless :P

Granted, it would be nice to have a non-destructive method that returns
the array minus the passed element[s]. Feel free to correct me if such
a method already exists, but I couldn't find one the other day when I
wanted it.