From: Bill Guindon <agorilla@...>
Date: 2006-03-12T13:08:14+09:00
Subject: Re: from Python to Ruby in 10 seconds

On 3/11/06, dblack@wobblini.net <dblack@wobblini.net> wrote:
> Hi --
>
> On Sun, 12 Mar 2006, Bill Guindon wrote:
>
> > On 3/11/06, Dave Burt <dave@burt.id.au> wrote:
> >> I find Logan's answers accurate and complete, except for one, which is a
> >> little complicated. Let me add a little to his answer.
> >>
> >> John M. Gabriele wrote:
> >>>> - Python uses _foo, __bar, and __baz__ underscore notation
> >>>> loosely for private references. Does Ruby have similar
> >>>> notions of "privacy"?
> >>
> >> Logan Capaldo wrote:
> >>> Method visibility can be controlled via the private, public, and
> >>> protected key words. You can always get past these of  course by use  of
> >>> #instance_eval for instance.
> >>
> >> In "foo.bar", bar is always a method, not a variable. What we call
> >> attributes are methods that behave like attributes. "foo.bar = baz" calls a
> >> method called bar=. We use attr_accessor, attr_reader and attr_writer to
> >> create attributes with their own variables. For example, "class Foo;
> >> attr_accessor :bar; end; foo = Foo.new"
> >
> > I found this a bit confusing.  Maybe....
> > attr_accessor, attr_reader and attr_writer can be used to create
> > attributes with their own variables.  They can also create the
> > appropriate set/get methods for those (or other) variables.
>
> If I can join the word-tweaking sweepstakes:  I don't think attributes
> really have "their own" variables.  Give this:
>
>    class C
>      attr_accessor :x
>    end
>
> the methods x and x= have no unique claim to, or ownership of, @x.
>
> Maybe one could say: The attr_* methods wrap instance variables in
> simple, like-named getter and/or setter methods.  Given a pair of such
> methods x and x=, wrapped around @x, objects of the class are said to
> have an attribute "x".  Or something.

Perhaps best said with "when you have no other methods that set/get @x"?

> > The method names need to passed as symbols:
> > class Foo
> >  private :bar
> > end
>
> You can use a string too (private "bar").

I sit corrected (he says, hoping to keep his 'standings' in the
'word-tweaking sweepstakes')

If nothing else, it serves as a reminder that I should buy your book ;)

>
> David
>
> --
> David A. Black (dblack@wobblini.net)
> Ruby Power and Light, LLC (http://www.rubypowerandlight.com)
>
> "Ruby for Rails" chapters now available
> from Manning Early Access Program! http://www.manning.com/books/black
>
>


--
Bill Guindon (aka aGorilla)
The best answer to most questions is "it depends".