From: Mark Hubbart <discordantus@...>
Date: 2005-05-30T02:55:52+09:00
Subject: Re: method visibility

On 5/28/05, Bob Aman <vacindak@gmail.com> wrote:
> More nubyness.  Apologies.
> 
> Ok, so, I have this rss feed caching system i'm working on.  Ideally,
> I'd like to have as little of the internal workings of the thing
> visible as possible.  I just want the programmer to interact with Feed
> and FeedItem objects, not the caching mechanisms.
> 
> It seems to me that I don't really want the programmer to be able to
> create instances of a FeedItem manually.  All FeedItems ought to be
> created automatically by a Feed object.  But it seems like ruby lacks
> the direct equivalent of c++'s "friend", so I guess I can't give
> access to the "new" class method only to Feed.

The ruby way, as i would interpret it, would be to make changes to
deter, but not prevent, the user-programmer from doing things you
don't want, and trusting them to take the warning.

For an example of this, take a look at complex.rb and rational.rb in
the stdlib. Both of those classes show different ways of doing this,
like replacing the #new method after aliasing it to #new2. This allows
people to work naturally with the class, and follows the ruby way. And
when you want to create a new version of the class in your code, call
#new2, instead.

cheers,
Mark