From: hemant <gethemant@...>
Date: 2006-10-20T23:33:12+09:00
Subject: Re: break from block

On 10/20/06, Farrel Lifson <farrel.lifson@gmail.com> wrote:
> On 20/10/06, Michael Studman <me@michaelstudman.com> wrote:
> > I'm not sure it's the Ruby way (I'm too new to Ruby to judge) but how
> > about:
> >
> > block = lambda{|i| i > 5 ? throw(:enough) : nil}
> > n = 10
> >
> > catch(:enough) do
> >    n.times &block
> > end
> >
> >
> > > I've just run into the following problem. Doing this:
> > > block = lambda{|i| i > 5 ? break : nil}
> > >  n.times &block
> > > raises a LocalJumpError, I assume because break is not valid from
> > > within a Proc object. Is there any way to get around this?
> > >
> > > Farrel
> > >
> > >
>
> I tried that but it's a performance killer (nearly 3 times as slow in
> my informal testing), which I'm trying to optimise for atm.
>
> Farrel
>
>

I think i got the error Farrel:

http://www.ruby-doc.org/core/classes/LocalJumpError.html

when you call 10.times {|i| break if i>5; p i}, it works because its
not the one object that is being passed around, but when you pass pass
a proc object to as an block to the method call, its initialized only
once and once you do a break from the proc, subsequent calls fail
because of LocalJumpError, because proc was terminated by :break( and
will get terminated by :redo, :retry, :next, :return, or :noreason.)

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