From: Robert Klemme <bob.news@...>
Date: 2004-11-03T19:38:48+09:00
Subject: Re: Programmatically and dynamically catching exceptions


"Logan Capaldo" <logancapaldo@gmail.com> schrieb im Newsbeitrag
news:4521f6680411022134451a94d1@mail.gmail.com...
> Thanks thats quite neat.
>
> On Wed, 3 Nov 2004 13:20:28 +0900, Yohanes Santoso
> <ysantoso-rubytalk@dessyku.is-a-geek.org> wrote:
> > Logan Capaldo <logancapaldo@gmail.com> writes:
> >
> >
> >
> > > Allright here was my idea which seems to have been shattered by the
> > > realities of Ruby.
> > >
> > > I was thinking of a class called Try. You would do something like
> > >
> > > class Try
> > > ...
> > > end
> > >
> > > tryblock = Try.new { #This block would normally be wrapped in a
begin...rescue
> > >                            }
> > >
> > > tryblock.add_exhandler(:SomeException) { |ex| some_code }
> > >
> > > tryblock.execute #or possibly tryblock.call ?
> > >
> > > Basically the idea was going to be you could subclass Try and
provide
> > > default sensible handling of your Exceptions (if you were writing a
> > > library for instance) . Users could then then wrap it in a
> > > begin...rescue block to catch other exceptions or use add_exhandler
to
> > > overide the default handler. (Possibly provide a way to get the old
> > > handler and and use it in the new).
> > >
> > > my idea was going to be that I could do something like
> > >
> >
> > class Try
> >   def execute
> >     begin
> >       user_proc.call(*user_proc_args)
> >     rescue Error => e
> >       elt = (exhandlers.select{|obj| e.class ==
obj.exception_class})[0]
> >       if elt
> >         elt.exception_handler.call(e)
> >       else
> >         raise e
> >       end
> >     end
> >   end
> > end

We can save three more lines :-)

class Try
  def execute
    begin
      user_proc.call(*user_proc_args)
    rescue Error => e
      elt = (exhandlers.select{|obj| e.class == obj.exception_class})[0]
      raise unless elt
      elt.exception_handler.call(e)
    end
  end
end

Kind regards

    robert