From: Robert Klemme <shortcutter@...>
Date: 2011-04-18T20:16:53+09:00
Subject: Re: [ANN] To Yield or Not to Yield: An Inferable Question

On Mon, Apr 18, 2011 at 11:46 AM, Michael Edgar <adgar@carboni.ca> wrote:
> It is the correct link, we had some unscheduled downtime. My apologies. Give it
> a couple minutes for the unicorns to kick in.

Now I see it.  Thanks!  This looks interesting and I think this is
something to muse about further.  On first glance I only noticed the
complete absence of another case of "optional block" apart from calls
guarded by block_given? or tests for &b parameter to be non nil:
caught exceptions

irb(main):003:0> def foo
irb(main):004:1> yield
irb(main):005:1> rescue LocalJumpError
irb(main):006:1> end
=> nil
irb(main):007:0> foo
=> nil
irb(main):008:0> foo { puts "called" }
called
=> nil

irb(main):009:0> LocalJumpError.ancestors
=> [LocalJumpError, StandardError, Exception, Object, Kernel, BasicObject]

irb(main):010:0> def bar; yield rescue LocalJumpError;end
=> nil
irb(main):011:0> bar
=> LocalJumpError
irb(main):012:0> bar { puts "called" }
called
=> nil

That will also be tricky since there are multiple exceptions that can
be caught to make the failed call "disappear" plus you can have
arbitrary nesting of begin - rescue - end blocks which can depend on
each other in bad ways (although these are more on the side of
pathological code).

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/