From: David Alan Black <dblack@...>
Date: 2001-09-02T02:55:06+09:00
Subject: [ruby-talk:20679] Re: RCR: non-bang equivalent to []=

Hello again --

On Sun, 2 Sep 2001, Tobias Reif wrote:

> Hi David,
>
>
> >>[]= is bang;
> >>so
> >>a version of []= that doesn't modify the receiver
> >>would be cool.
> >>
> > I'm sorry -- I don't understand.  What exactly is supposed to happen?
> >
> >   a = [1,2,3,4]
> >   a.non_bang_set(0) = 100
> >   a                      # => [1,2,3,4]
>
>
> Would the following make sense?
> The exact syntax doesn't matter to me, i just would like to get a
> non-bang []=
  ^^^^^^^^^^^^

That phrase sounds self-contradictory to me :-)  Anyway....


> Array#set_at
>
> a = ["a", "b", "c"]
> a.set_at 0,"x" -> ["x", "b", "c"]
> a -> ["a", "b", "c"]
>
> Array#set_at!
>
> a = ["a", "b", "c"]
> a.set_at! 0,"x" -> ["x", "b", "c"]
> a -> ["x", "b", "c"]


Well, since presumably you'd want to save the return value, it would
generally be:

  b = a.set_at(0,"x")

as opposed to, say,

  (b = a.dup)[0] = "x"

or
  b = a.dup
  b[0] = "x"

Personally I find the 'dup' ones clearer.  That may be because they
are :-) and/or because the word 'set' just doesn't evoke
non-modification to me.


David

-- 
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav