为什么要在Perl中返回散列或散列引用？

文件a.pl

my %hash = build_hash();
# Do stuff with hash using $hash{$key}
sub build_hash
{
    # Build some hash
    my %hash = ();
    my @k = qw(hi bi no th xc ul 8e r);
    for ( @k )
    {
        $hash{$k} = 1;
    }

    # Does this return a copy of the hash??
    return %hash;
}

文件b.pl

my $hashref = build_hash();
# Do stuff with hash using $hashref->{$key}
sub build_hash
{
    # Build some hash
    my %hash = ();
    my @k = qw(hi bi no th xc ul 8e r);
    for ( @k )
    {
        $hash{$k} = 1;
    }

    # Just return a reference (smaller than making a copy?)
    return %hash;
}

文件c.pl

my %hash = %{build_hash()};
# Do stuff with hash using $hash{$key}
# It is better,because now we don't have to dereference our hashref each time using ->?

sub build_hash
{
    # Build some hash
    my %hash = ();
    my @k = qw(hi bi no th xc ul 8e r);
    for ( @k )
    {
        $hash{$k} = 1;
    }

    return %hash;
}