From: Robert Klemme <bob.news@...>
Date: 2004-03-05T17:59:49+09:00
Subject: Re: rescue inside block -> syntax error


"Gavin Sinclair" <gsinclair@soyabean.com.au> schrieb im Newsbeitrag
news:71397207684.20040305112546@soyabean.com.au...
> On Friday, March 5, 2004, 4:24:41 AM, Kent wrote:
>
>
> >> +1, and IIRC that rcr just felt in some limbo.. What was wrong with
it
> >> ?
>
> > For starters, it would start drifting do..end blocks and {..} blocks
> > apart, unless you'd allow it in those too.
>
> > {|this|
> >    this.will
> > ensure
> >    self.gag
> >    other_who_like_curly_braces.gag
> > }
>
> But what is the alternative?  I mean, how often do you see code like
> this?
>
>   meth(arg) {
>     begin
>       # ...
>     rescue
>       # ...
>     end
>   }

Rarely enough, true.

There's an issue that limits the usability of do..ensure..end: Typically
you do resource allocation *outside* the begin..end because you don't want
the ensure clause to be executed if something during init fails:

container.each do |obj|
  processor = create_processor_in_a_way_that_might_throw()

  begin
    processor.do_work()
    processor.do_more_work()
  ensure
    processor.cleanup()
  end
end

or

def File.open(file, mode="r")
  io = create_io_and_throw_if_not_found(file)

  begin
    yield io
  ensure
    io.close()
  end
end

In all these cases you don't gain anything by having do..ensure..end.

Kind regards

    robert