From: dblack@...
Date: 2002-12-05T11:47:46+09:00
Subject: Re: Enumerable#map_with_indices (was Re: Conditional block operations)

Hi --

On Thu, 5 Dec 2002, Paul Duncan wrote:

> * David A. Black (dblack@superlink.net) wrote:
>
> [snipped]
> > Otherwise I think you have to do some kind of pre-filtering.  If we had
> > map_with_indices, you could do:
> >
> >   myarray.map_with_indices {|e,i| e + ", " if i % 2 == 0} .compact
> >
> > but we don't.  (Hint, hint.)
>
> #!/usr/bin/env ruby
>
> module Enumerable
>   def map_with_indices
>     a = [] # should this be "self.class.new"?
>     each_with_index { |o, i| a << yield(o, i) }
>     a
>   end

It was more a hint to Matz, though I think mwi is off the table :-)  As
for the self.class.new thing, I think it should be an array, since
that's what #map returns.


David

-- 
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav