From: Dan Doel <djd15@...>
Date: 2003-11-20T15:38:51+09:00
Subject: Re: x.f! RCR

Well, I agree.  However, I would argue that there should be a #delete 
and #delete! for that very reason.

I was merely arguing that #delete doesn't necessarily have to modify the 
array in place you could have:

a = ["a", "b", "b", "c"]

b = a.delete "b"

p a # => ['a', 'b', 'b', 'c']
p b # => ['a', 'c']

And then #delete! would make sense as you describe.

As I glance at the documentation, there is no method that does this 
currently, although it could be easily
done with #map and #compact.

In fact, all destructive methods could be done this way. Some would be 
somewhat stupid, such as #clear
which would just return an empty array, which is fairly useless except 
in the #clear! case. The downside of
the a.f! => a = a.f proposal is that sometimes the former can be 
implemented much more efficiently than the
latter.

Oh, and when I said "side-effects" in my last mail, I actually meant 
side-effects due to assignment. I realize
there are others such as reading and writing data, and I'm sure you're 
right that Scheme doesn't use ! in those
cases.  However, I believe there's a convention that if a function 
modifies one of the arguments (that is, uses
(set!) with them), the function also includes an ! in the name.

Regards.

- Dan