From: Victor Shepelev <vshepelev@...>
Date: 2006-04-01T19:36:57+09:00
Subject: Re: (Static) Constructors/Destructors in Ruby



> -----Original Message-----
> From: Benjohn Barnes [mailto:benjohn@fysh.org]
> Sent: Saturday, April 01, 2006 1:25 PM
> To: ruby-talk ML
> Subject: Re: (Static) Constructors/Destructors in Ruby
> 
> 
> On 1 Apr 2006, at 11:10, Victor Shepelev wrote:
> > I like block idea, but must say that blocks can't give full
> > replacement for
> > C++'s RAII ideom:
> >
> > C++:
> >
> > {
> >   File f1,f2,f3;
> >   Socket s1,s2;
> >   Database d;
> > } //here all f1,f2,f3,s1,s2,d being closed
> >
> > Ruby:
> >
> > ???
> 
> :) It's such a fresh beautiful day outside... and here I am talking
> tech, when spring is springing :)

Hmmm... Not so beautiful/springy day in Kharkov, Ukraine :)

> Ok, in Ruby, each of those resources could easily be turned in to a
> method that will run a block. What you want to be able to do then, is
> easily compose those methods in to one, and have that run something
> within the context of resources being available?
> 
> Something along the lines of (unchecked code warning!)...?
> 
> def run_with_resources(*resources, &block)
> 	if resources == []
> 		yield
> 	else
> 		send(resources.slice(0)) {run_with_resources(*resources,
> &block)}
> 	end
> end
> 
> You can then do...
> 
> run_with_resources
> (:file_handle, :db_connection, :socket_and_things, :other_groovy_bits) d
> o
> 	#Wooo - look at all these resources!
> end
> 
> It wouldn't be a big extension to collect up the resources passed in,
> and pop them in a map, or something. I don't think it would be hard
> to give the resources arguments either.

Yes, I know all those trick (I'm not a VERY newbie :) - my point was "blocks
not always good alternative for RAII".

BTW, I recalled I saw some library at RAA, which does the stuff. But I don't
remember it's name (because in real life it is not as necessary as in dumb
examples ;) 
 
> Cheers,
> 	Ben

Victor.