Well... 

my $hash;
$hash{foo} = bar;

[download]
  • Creates a lexical scalar named $hash
  • Assigns 'bar' to the key 'foo' in the global variable %hash (or, more accurately, %main::hash)

    If you meant: 

    my %hash;
$hash{foo} = 'bar';

#Versus

my $hash = {};
$hash->{foo} = 'bar';

    [download]

    Then there is still a difference. In the first, you create a lexical hash named %hash, then assign a value to one of it's keys. In the second you create a lexical scalar which contains an anonymous reference to a hash.

    To examine the difference, run this: 

    #!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

print "A lexical hash:\n";
my %hash;
$hash{foo} = 'bar';
print Dumper(\%hash);

print "A lexical hash *reference*:\n";
my $hash = {};
$hash->{foo} = 'bar';
print Dumper(\$hash);

    [download]
    Note how the variable in the second case "points to" (is a reference to) the actual hash, while the first case is just the hash. I highly suggest reading up on references, and man perlvar -- the nuances are important and often incredibly useful. ;-)

    radiantmatrix
    require General::Disclaimer;
    "Users are evil. All users are evil. Do not trust them. Perl specifically offers the -T switch because it knows users are evil." - japhy

    In reply to Re^3: when is "my" not necessary? by radiantmatrix
    in thread when is "my" not necessary? by argv

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