From: Daniel Finnie <dan@...>
Date: 2008-05-19T08:39:55+09:00
Subject: Re: How to wrap either forkoff or map depending on a config variable?

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Hi,

To pass a block as a block to another function, put an ampersand before the
variable name:

map &block
forkoff &block

If you are interested in performance, know that using the &block notation
for blocks is slower than using the block_given? and yield semantics.

Dan

On Sun, May 18, 2008 at 4:03 PM, Shot (Piotr Szotkowski) <shot@hot.pl>
wrote:

> Hello, good people of ruby-talk.
>
> I'm trying to write an Enumerable#parallel method that, depending on
> a config option (retrieved inside it) would end up being an alias for
> either Enumerable#map or Enumerable#forkoff.
>
> (I know calling enum.forkoff(1) should equal enum.map, but I need
> the wrapper to call #map, as forkoff doesn't work under JRuby.)
>
> I'm quite new to the idea of blocks/closures, and while I love using
> them, I'm still not sure how to write such a method. What I'm looking
> for is something like this:
>
> module Enumerable
>  def parallel &block
>    if Config.processes =3D=3D 1
>      # call map with the passed block
>    else
>      # call forkoff with the passed block
>    end
>  end
> end
>
> Ideally, the call to forkoff would pass Config.processes as its
> first param =96 i.e., calling enum.parallel {=85} would mean calling
> enum.forkoff(Config.processes) {=85}
>
> -- Shot
> --
> An Emacs reference mug is what I want. It would hold
> ten gallons of coffee.     -- Steve VanDevender, asr
>

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