From: Robert Klemme <shortcutter@...>
Date: 2007-05-21T23:35:05+09:00
Subject: Re: using Enumerable when each has arguments?

On 21.05.2007 15:27, Trans wrote:
> 
> On May 21, 6:41 am, "Erwin Abbott" <erwin.abb...@gmail.com> wrote:
>> Hi
>>
>> I've written a number of classes which would benefit from the
>> Enumerable mixin, but my #each method requires arguments.  These are
>> usually to specify the range of values, like Fibonacci#each(first,
>> last) or whatever.  Since Enumerable's #map, #collect, etc don't take
>> arguments, how should I proceed?  I would be okay with wrapping the
>> Enumerable methods I need, but that doesn't seem possible.  Do I just
>> have to implement my own #map, #to_a, etc?
> 
> The standard response is "use enumerator and to_enum". but if you feel
> like me, that's equivalent to tying knots in your spaghetti noodles to
> save money on rotini.

I on the other hand am a big fan of Enumerator. :-)

> I heard rumor that a future Ruby will ultimately pass thru each
> parameters, but in the mean time you can have a go with Facets
> enumerablepass.rb (http://facets.rubyforge.org).

That's a good solution.

> An alternative is to use a functor (a function delegator) for your
> parameters, eg.
> 
>   f = Foo.new
>   f.range(1,5).each{|x| p x}

... which is basically the same as using to_enum - only less portable; 
to_enum works with *all* methods. :-)

Kind regards

	robert