From: Markus <markus@...>
Date: 2004-10-13T02:14:30+09:00
Subject: Re: Ruby Directions (was Re: quality of error messages)

On Tue, 2004-10-12 at 09:36, Austin Ziegler wrote:
> On Wed, 13 Oct 2004 01:28:23 +0900, Markus <markus@reality.com> wrote:
> >      The odd thing is, all you are generally getting with them is a bit
> > of syntactic sugar.  Consider the relationship between:
> > 
> >     s = gsub(p,v)
> >     s.gsub!(p,v)
> > 
> >     i = i + k
> >     i += k
> > 
> > Unless you have lent a friend a reference to s and are using it to send
> > secret messages, you aren't really depending on the mutability of
> > strings so much as the modifability of variables.
> 
> The two aren't equivalent. In fact, the following holds true in Ruby:
> 
>     def gsub(search, replace)
>       self.dup.gsub!(search, replace)
>     end
> 
> So String#gsub! isn't at all equivalent to i += k, because:
> 
>     s = t = "foo"
>     s.gsub!(/$/, "t") # => "foot"
>     puts t # => "foot"

     That's exactly what I meant by the phrase "Unless you have lent a
friend a reference to s and are using it to send secret messages" -- t,
in this case, being s's friend.  My point was that:

>     s = t = "foo"

isn't all that common.  It's as likely when it does happen that the user
(especially the nuby) is expecting it to behave like "s = (t =
"foo").dup -- in other words, the whole reason they are assigning to
both s and t is so that they will have "two copies" of the string.

> I know that I use String#<< quite a bit, which means that nearly
> everything that I do depends on the mutability of Strings. (Well, to
> be more accurate, I use #<< quite a bit, and assume that it will Do
> The Right Thing, which means that I depend on the mutability of
> Strings).

     Sure.  For that matter, I do as well.

     *smile*  So are you wanting Integer to be mutable too?

-- Markus (a.k.a. "the devils advocate")