On Sun, Apr 6, 2008 at 11:51 PM, Casey <heavyccasey@xxxxxxxxx> wrote:
> I hit reply-all... now am I suddenly subscribed to Perl and Ruby lists!?!
Huh, didn't notice the cross-posting. But no, you're not subscribed
to any new lists.
Since we're cross-posting, the translation of my sample would be
apropos. Here are a few different takes on a loopless versions in
Ruby. Given:
color = { :apple => :red, :ruby => :red, :banana => :yellow }
This is, I think, the most straightforward:
color.keys.find_all { |k| color[k] == :red }
But having to repeat the hash name is inelegant. Which leads us to this:
color.find_all { |k,v| v == :red }.collect { |p| p[0] }
Building up a list from the elements of a Hash would seem to be a
natural application of Hash#inject, although the fact that the inject
block has to return the accumulator makes it a little less elegant
than it could be, IMO:
color.inject([]) { |a,p| a << p[0] if p[1] == :red; a }
In Perl5 I don't have a better solution than the first one above:
my %color = ( apple => 'red', ruby => 'red', banana => 'yellow');
grep { $color{$_} eq 'red' } keys %color;
--
Mark J. Reed <markjreed@xxxxxxxx>
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