From: Eric Mahurin <eric_mahurin@...>
Date: 2005-10-13T07:38:43+09:00
Subject: Re: Default argument values for blocks

--- "Ara.T.Howard" <Ara.T.Howard@noaa.gov> wrote:

> On Thu, 13 Oct 2005, Sean O'Halpin wrote:
> 
> > On 10/12/05, Eric Mahurin <eric_mahurin@yahoo.com> wrote:
> >> Or maybe if "eval" became a keyword like you mentioned
> above
> >> and it could also take a block, you could do this instead:
> >>
> >> b=1
> >> eval {|;b|
> >>  b=5
> >>  p b # => 5
> >> }
> >> p b # => 1
> >
> > +1
> >
> > Any chance of eval taking a block ~and~ a specific binding,
> e.g.
> >
> >  eval &block, binding
> >
> > (though this breaks current argument parsing rules).
> >
> > Sean
> 
> eval(binding, &block) works.  the eval(string) method just
> needs to check it's
> arg type.

It doesn't need to check type.  If there is a block, the
optional arg would be a binding.  Otherwise, the first arg is
the eval string and the optional second arg is the binding.

If this is possible, it would be good to be able to do this to
a general Proc.  But, if not you could still make the
functionality with the above Kernel#eval:

class Proc
  def rebind(binding)
    Proc.new {
      eval(binding,&self)
    }
  end
end

Of course you have the same problem that we have with
instance_eval - you can't pass any args.  Might as well think
about making that work with eval too.




		
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