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Re: strange map behavior

by ikegami (Patriarch)
on Feb 25, 2008 at 17:27 UTC ( [id://670055]=note: print w/replies, xml ) Need Help??


in reply to strange map behavior

Perl sometimes guesses a block is an anonymous hash constructor and vice-versa. 
my %h = map {; $_ => $_ } @arr;
             ^
             |
       force a block.

[download]
my @a = map +{ $_ => ord($_) }, @arr;
            ^
            |
      force a hash

[download]

By the way, why are you using "$_" instead of just $_?

Replies are listed 'Best First'.
Re^2: strange map behavior
by jeanluca (Deacon) on Feb 25, 2008 at 19:24 UTC
    I tried to build a new hash out of an array with hashes, something like:
    #! /usr/bin/perl -l
use strict;
use warnings ;

my @arr = ( {'a' => 'x', 'b' => 'y', 'c' => 'z'}, 
            {'a' => 'x1', 'b' => 'y1', 'c' => 'z1'} ) ;
my %h = map {;"$_->{'a'}_$_->{'c'}" => $_->{'b'} } @arr ;
print "$_ -- $h{$_}" foreach ( keys %h ) ;

    [download]
    Thnx
    LuCa
[reply]
[d/l]
      That makes more sense. But you might want to use join to increase readability. 
      my %h = map { join('_', $_->{'a'}, $_->{'c'}) => $_->{'b'} } @arr ;

      [download]
[reply]
[d/l]
[select]

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