From: Michael Neumann <mneumann@...>
Date: 2003-11-20T18:16:01+09:00
Subject: Re: x.f! RCR

On Thu, Nov 20, 2003 at 03:38:51PM +0900, Dan Doel wrote:
> 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"

delete actually returns the removed element ("b" in this case) or nil if
no element to delete was found. It does not return the array.

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

  a.delete "b"   # => "b"
  a.delete "b"   # => nil  (no more "b" in a) 
  a.delete "x"   # => nil  (no "x" in a)

So it can't be modified for non-destructive deletion this way. 

What you want in #reject (indeed #reject is more general than #delete,
as it's part of Enumerable, not just Array).

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

  b = a.reject {|e| e == "b"} 

Here the #reject! method works as expected. 
 
Regards,

  Michael