From: David Pollak <pollak@...>
Date: 2006-07-01T02:57:15+09:00
Subject: Re: Reflection brakes encapsulation

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The same reflection issues are present in Java and C#.  I know of no
language and/or runtime that completely enforces protection of private
methods.

On 6/29/06, Valentin Samareanu <vsamareanu@itcnetworks.ro> wrote:
>
> Ok. I'll take it as it is and try to do nice and unharmful thinks with it.
>
> Thanks
>
> ----- Original Message -----
> From: "Robert Klemme" <shortcutter@googlemail.com>
> To: "ruby-talk ML" <ruby-talk@ruby-lang.org>
> Sent: Thursday, June 29, 2006 1:39 PM
> Subject: Re: Reflection brakes encapsulation
>
>
> > 2006/6/29, Valentin Samareanu <vsamareanu@itcnetworks.ro>:
> > >
> > > However, there is something related to OO concepts that I think, in
> Ruby, is looking for troubles. More exactly, the encapsulation can be
> broken
> using reflection. Here is a piece of cod that illustrates this:
> >
> > <snip/>
> >
> > > As you can see, I declared the method incCount private as it changes
> the
> object's internal state
> >
> > You can even go further and directly modify instance variables with
> > instance_variable_set and instance_variable_set.
> >
> > > But, surprise, the method is not quite genuine private. It can be
> called
> outside the class using reflection.
> > > My question is if it's OK to let code outside the class to change the
> internal state of an instance of that class? I mean why should we bother
> making methods private in the first place if they can be called outside
> the
> class anyway?
> >
> > Ruby prevents normal usage of private methods but still let's you use
> > them if you know what you do. So the answer is, yes, bother to make
> > things private that should stay private.  Anybody messing with the
> > innards of your classes will be immediately punished if he does it in
> > non conforming ways - but he *can* do it if needed. That's Ruby's
> > pragmatic approach.
> >
> > > Is it a known behaviour or it has just gone unnoticed so far?
> >
> > Umm, Ruby has been around for some while now (meaning years) - such a
> > fundamental design cannot go unnoticed for such a long time.
> >
> > Kind regards
> >
> > robert
> >
> > --
> > Have a look: http://www.flickr.com/photos/fussel-foto/
> >
>
>
>


-- 
--------
David Pollak's Ruby Playground
http://dppruby.com

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