Re: Syntax explanation required

Two alternative ways derived from: perldoc -q duplicate

my %seen;
my @uniq = grep { !$seen{$_}++ } keys(%hash1), keys(%hash2);
[download]

use List::MoreUtils qw(uniq);
my @uniq = uniq( keys(%hash1), keys(%hash2) );
[download]

Comment on Re: Syntax explanation required Select or Download Code

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Re^2: Syntax explanation required (uniq) by LanX (Saint) on Jan 03, 2013 at 01:58 UTC
I was meditating about advising `List::MoreUtils:uniq` as a best practice, cause I thought it prevents any stringification problems.š Unfortunately it doesn't! :( `DB<125> $a=["A"] => ["A"] DB<126> $b=["B"] => ["B"] DB<127> @a=($a,"$a",$b,"$b") => (["A"], "ARRAY(0x96cb0f0)", ["B"], "ARRAY(0x96cfd80)") DB<128> @b= uniq @a => (["A"], ["B"])` [download] thats quite disappointing for an XS-module ... EDIT: Well at least it preserves order... Cheers Rolf š) I should explain, the problem with using hashes for set operations is that keys are stringified, that means working with anything which isn't a string or at least a scalar comes with a risk. Practically it's not possible to safely use a ref as a key because of the resulting string is irreversible. `DB<130> $h{$a}=5 => 5 DB<131> %h => ("ARRAY(0x96d1f00)", 5)` [download] UPDATE: improved code example...	[reply] [d/l] [select]
Re^3: Syntax explanation required (uniq) by ghosh123 (Monk) on Jan 03, 2013 at 12:50 UTC
Thank you all. Very helpful !!!	[reply]