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Re^2: Perl Idioms Explained - keys %{{map{$_=>1}@list}}

by Aristotle (Chancellor)
on Aug 04, 2003 at 20:12 UTC ( #280778=note: print w/ replies, xml ) Need Help??


in reply to Re: Perl Idioms Explained - keys %{{map{$_=>1}@list}}
in thread Perl Idioms Explained - keys %{{map{$_=>1}@list}}

Note that this is slightly broken as is. To be entirely correct, you have to say

my (%seen, $seen_undef); my @uniq = grep defined() ? !$seen{$_}++ : !$seen_undef++, @list;
Of course, if you're fiddling with objects which cannot be compared for equity by stringification, it is still broken.

Makeshifts last the longest.


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Re3: Perl Idioms Explained - keys %{{map{$_=>1}@list}}
by dragonchild (Archbishop) on Aug 04, 2003 at 20:14 UTC
    Of course, if you're fiddling with objects which cannot be compared for equity by stringification, it is still broken.

    Well, so is every uniquification based on the keys of a hash! The point still stands that grep is faster than the original idiom presented, by orders of magnitude, if still as memory-hungry.

    ------
    We are the carpenters and bricklayers of the Information Age.

    The idea is a little like C++ templates, except not quite so brain-meltingly complicated. -- TheDamian, Exegesis 6

    Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.

      I didn't dispute that. :) I just pointed out some of the more subtle points to keep in mind here.

      Makeshifts last the longest.

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