in reply to A curious case of of my()

$href is empty, since it is not passed into foo. hence @array ends up being a package variable and not a lexical variable.
your code 
sub foo{
        my $var = shift;
        my $href = shift;
        my @array = $href->{pass_in} if defined $href and exists $href
+->{pass_in};
        push @array, $var;

        print "contents : @array\n";
}

foo(1);
foo(2);

[download]
This gives
contents : 1
contents : 1 2

However, commenting out the unused href code and declaring array as a lexical like:

sub foo{
        my $var = shift;
        my @array; 
        #my $href = shift;
        #my @array = $href->{pass_in} if defined $href and exists $hre
+f->{pass_in};
        push @array, $var;

        print "contents : @array\n";
}

foo(1);
foo(2);

[download]
gives

contents : 1
contents : 2

I hope for nothing. I fear nothing. I am free.

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Re^2: A curious case of of my()
by shmem (Chancellor) on May 05, 2011 at 10:34 UTC
    $href is empty, since it is not passed into foo. hence @array ends up being a package variable and not a lexical variable.

    As others have pointed out, that's wrong. my creates lexicals at compile time. It doesn't have a our fallback. The 'if' modifier with a false condition inhibits the opcode which clears the lexical at runtime. 

    our @array; # package vaiable
@array = qw( foo bar );

sub foo{
        my $var = shift;
        my $href = shift;
        my @array = $href->{pass_in} if defined $href and exists $href
+->{pass_in};
        push @array, $var;

        print "contents : @array\n";
}

print "outer scope - contents : @array\n";

foo(1);
foo(2);

print "outer scope - contents : @array\n";

__END__
outer scope - contents : foo bar
contents : 1
contents : 1 2
outer scope - contents : foo bar

    [download]

    As you can see, the variable @array inside the sub is a lexical.

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