From: Robert Klemme <bob.news@...>
Date: 2005-05-08T00:29:33+09:00
Subject: Re: object reference handle (like perl's reference to scalar)


"Dave Burt" <dave@burt.id.au> schrieb im Newsbeitrag 
news:HS2fe.5993$31.2330@news-server.bigpond.net.au...
>>> My Ref module at http://www.dave.burt.id.au/ruby/ref.rb now tries to 
>>> behave as much like the referred-to object as possible. You above Module 
>>> case statement will work with Refs now, as will uses of respond_to? 
>>> is_a? kind_of? and class. A Ref will additionally respond_to a few 
>>> unique methods (ie deref, deref=).
>>
>> Hm, and what do you do if you have to test for Ref objects?
>
> variable.ref?
>
>> I didn't follow this thread thoroughly, all I can say is that I 
>> personally haven't missed refs in Ruby until now.  There are certainly 
>> things that speak in favour of your concept.
>>
>> But there are also problems.  Ironically some of them seem to be caused 
>> by the fact that you make a Ref behave like the original instance as much 
>> as possible.  That way Ref usage is more implicit than explicit and this 
>> can lead to confusion or subtle errors due to aliasing (i.e. you think 
>> you got a copy of something and modify it and some other piece of code 
>> breaks because it was just a ref).
>
> You're right about that. I prefer the new implementation:
>  Ref = Struct.new(:deref)
>
>> <soapbox>
>> It still might be worthwile, I just get the feeling that people try to 
>> stuff things from other programming languages into Ruby because they 
>> found them cute / useful / the only way to solve certain things in that 
>> language.  IMHO programming languages are different for a reason and 
>> often it's much better to adhere to the old saying "when in Rome do as 
>> the Romans do"... :-)
>> </soapbox>
>
> I don't think what I've done here is anything like that.

I had to place that comment in some of these threads that I feel we're seing 
more and more recently.  I probably didn't pick the most appropriate one... 
:-)

> The concept of a reference here is just a wrapper or pointer, and it has 
> to have a use. Sure, it causes problems in C and Perl, and Ruby definitely 
> offers more elegant tools fo most of the problems that are solved in those 
> languages with pointers, but I'm coming from a Rubyist's perspective here, 
> and all I'm proposing is a new container, for a single object.
>
> And I think Austin's PDF::Writer example is one case where it's useful 
> (that is, passing an object by reference into a method so the method can 
> replace the object).

Yuck, may well be.  On a side note, the fact that ruby methods can return an 
arbitrary number of objects is a really great thing, that can also help with 
some of these replacement problems.

Kind regards

    robert