From: Robert Dober <robert.dober@...>
Date: 2008-12-05T01:28:40+09:00
Subject: Re: Enumerable#select used to return actual values

On Thu, Dec 4, 2008 at 5:07 PM, Yukihiro Matsumoto <matz@ruby-lang.org> wrote:
> Hi,
>
> In message "Re: Enumerable#select used to return actual values"
>    on Fri, 5 Dec 2008 00:47:45 +0900, Trans <transfire@gmail.com> writes:
>
> |> (1..10).collect{ |a| a * a if a > 5 }.compact
> |>
> |> The only time this doesn't work is when you want to preserve nils in
> |> your original array.
> |
> |And that's exactly what I suggested for #compact, to take a block but
> |faster b/c it's one pass.
>
> I don't deny the existence of use case of such method (although I
> cannot think of any realistic one right now), but its name should not
> be #compact, since it does far more than compacting the receiver.
>
>                                                        matz.
>
>
Hmmm
just a little brainstorming on this
[1, nil, false].compact --> [1]
[1, nil, false].compact_by{ |x| x.nil?} --> [1, false]

o = Object::new
a.collect{ |x| some_condition(x) ? x : o}.compact_by{ |x| x==o}

But actually the implementation is *easy* ;)
module Enumerable
   alias_method :compact_by, :reject ### ;)
end

However what about

module Enumerable
   alias_method :__old_reject__, :reject
   def reject( *args, &blk )
        raise SomeDescriptiveError unless blk.nil? || args.empty?
        return __old_reject__( &blk ) if blk
        __old_reject__{ |x| args.include? x }
   end
end

I guess I might put this into Labrador ;)

Cheers
Robert

or




-- 
Ne baisse jamais la tête, tu ne verrais plus les étoiles.

Robert Dober ;)