From: Gregory Brown <gregory.t.brown@...>
Date: 2010-01-28T00:09:17+09:00
Subject: Re: Inconsistency - map/collect not returning enumerator

On Wed, Jan 27, 2010 at 8:29 AM, Brian Candler <b.candler@pobox.com> wrote:
> This seems a bit of an anomoly:
>
>>> x = [1,2,3].map
>>> x.each { |y| y*2 }
> => [1, 2, 3]            # I was expecting [2, 4, 6]
>
> It seems that Array#map and Enumerable#map without a block return just
> an Array. However most other Enumerable methods return an Enumerator,
> even #each (which is pretty useless, since the Enumerator maps #each to
> #each)
>
>>> RUBY_DESCRIPTION
> => "ruby 1.8.7 (2009-06-12 patchlevel 174) [x86_64-linux]"

> Anybody got a good explanation for this?

Yes.  You're using Ruby 1.8.7, which is, in and of itself, an anomaly :)

But this may be to preserve compatibility with Ruby 1.8.6:

>> RUBY_VERSION
=> "1.8.6"

# NOT OK TO CHANGE BEHAVIOR
> [1,2,3].map
=> [1, 2, 3]

# OK TO ADD BEHAVIOR
>> [1,2,3].select
LocalJumpError: no block given
        from (irb):3:in `select'
        from (irb):3