From: MonkeeSage <MonkeeSage@...>
Date: 2007-12-17T22:25:10+09:00
Subject: Re: Is there any way to pass further the "hidden" block?

On Dec 17, 6:52 am, Trans <transf...@gmail.com> wrote:
> On Dec 17, 3:11 am, "Chiyuan Zhang" <plus...@gmail.com> wrote:
>
>
>
> > Like this:
>
> > def foo
> >   yield
> > end
>
> > def bar(&brk)
> >   foo(&brk)
> > end
>
> > bar { puts "foo" }
>
> > What I want to know is: is there any way to define `bar' like this:
>
> > def bar
> >   foo
> > end
>
> > so that foo will get the block passed to bar? I want to know this
> > because I learn fromhttp://www.pluralsight.com/blogs/dbox/archive/2006/05/09/23068.aspx
> > that the implicit block is much faster than explicitly passing it
> > as &brk . I know one solution is
>
> > def bar
> >   foo { yield }
> > end
>
> > but that create another block, not the original one.
>
> Do you mean, is there a keyword #block to go along with #block_given?
> and #yield? As far as I know, there is no way to pass the block except
> via an explicit reference.
>
> But I think explicit may be the future. I'm pretty sure I've heard
> some chatter about getting rid of #block_given? Technically I would
> think it possible to all but eliminate the speed difference between
> explicit and implicit --3x seems very high.
>
> T.

On further testing it appears that in situations where can create a
proc and reuse it, the performance comes much closer (although the
implicit version says the same?!):

require "benchmark"
def implicit_blk
  yield "baz"
end
def explicit_blk(&blk)
  blk.call("baz")
end
n = 1_000_000
prc = lambda { | y | y }
Benchmark.bm(10) { | x |
  x.report("implicit") { n.times { implicit_blk(&prc) } }
  x.report("explicit") { n.times { explicit_blk(&prc) } }
}

# =>
                user     system      total        real
implicit    3.730000   0.520000   4.250000 (  4.479818)
explicit    6.000000   0.580000   6.580000 (  6.763514)

...wonder why?

Regards,
Jordan