From: dblack@...
Date: 2006-03-29T00:56:25+09:00
Subject: Re: Why do some methods names which replace the content in place doesn't have the "!" sign?

Hi --

On Wed, 29 Mar 2006, Gregory Seidman wrote:

> On Wed, Mar 29, 2006 at 12:00:32AM +0900, dblack@wobblini.net wrote:
> } On Tue, 28 Mar 2006, Robert Dober wrote:
> } >and how can one modify a receiver without modifying its instance variables,
> }
> }   str = "hello"
> }   str.replace("goodbye")
> }
> } I've changed str without any instance variables being involved.  Same
> } with:
> }
> }   array = [1,2,3]
> }   array.pop
> }
> } and so forth.
>
> It's a technicality. Consider strings. Their internals are under the hood,
> so you claim that no instance variables are involved. This is not
> technically accurate. Object state happens to be held in C variables rather
> than Ruby variables (which are, of course, backed by C variables), but they
> are most certainly instance variables. Are you trolling or do you actually
> believe you are right?

I've been using Usenet since 1990 and never trolled.  I'm not going to
start now.

I'm talking about Ruby, not C.  In Ruby, you can modify a receiver
without changing its instance variables -- in fact, you can modify a
receiver that doesn't *have* any instance variables.

irb(main):001:0> s = ""
=> ""
irb(main):002:0> s.replace("abc")
=> "abc"
irb(main):003:0> s.instance_variables
=> []

The term "instance variable" has a specific and unambiguous meaning in
Ruby.


David

-- 
David A. Black (dblack@wobblini.net)
Ruby Power and Light, LLC (http://www.rubypowerandlight.com)

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