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You might remember that map, sort and grep can be chained and they always accept and return lists...

Hm. Passing a listified hash (mixed keys and values in random order) to any of those constructs is a completely pointless exercise.

That is after all, why you are having to define an hgrep yourself.

Better methinks to pass hgrep and hmap a reference to the hash, call the callback with pairs, and have them return a list.

At least then they serve a purpose:

#! perl -slw use strict; use Data::Dump qw[ pp ]; sub hgrep (&\%) { my( $code, $href ) = @_; map{ local @_; $code->( @_ = each %$href ) ? @_ : () } 1 .. keys %$href; } sub hmap (&\%) { my( $code, $href ) = @_; map{ local @_; $code->( @_ = each %$href ) } 1 .. keys %$href; } my %h = 'a'..'z'; print join ' ', hgrep{ $_[0] =~ /[a-m]/ } %h; print join ' ', hmap{ "$_[0] => $_[1]" } %h; my %orig = ( cat => 22, dog => 23, category => 66, catalyst => 77, cataclysm => 88, dogma => 89, dogstar => 92, ); my %h2 = hgrep{ $_[0] =~ /^cat/ } %orig; pp\%h2; __END__ C:\test>hfp e f a b m n c d k l g h i j w => x e => f a => b m => n s => t y => z u => v c => d k => l q => r +g => h i => j o => p { cat => 22, cataclysm => 88, catalyst => 77, category => 66 }

hsort is left as an exercise.


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In reply to Re^7: Is there any difference between prototype % and @ ? by BrowserUk
in thread Is there any difference between prototype % and @ ? by LanX

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