I think it's easiest to see what bless does by constructing an object and method without any module or package. Here's a bare-bones object with a single method.

# a method - get/set the value
sub Foo::value () :lvalue { ${$_[0]} }

# make three references to two things
my ($foo, $bar) = (do { my $v = 1; \$v }) x 2; # 2 refs to same $v
my $baz         =  do { my $v = 1; \$v };      # different $v

# . . . and a fourth
my $quux = bless $foo, 'Foo';

printf "\$foo\t%s\n\$bar\t%s\n\$baz\t%s\$quux\t%s\n",
       $foo, $bar, $baz, $quux;

print 'value is ', $foo->value(), $/;
$bar->value() = 10;
print 'now, ', $quux->value(), $/;

__END__
$foo    Foo=SCALAR(0x80591e8)
$bar    Foo=SCALAR(0x80591e8)
$baz    SCALAR(0x8059248)
$quux   Foo=SCALAR(0x80591e8)
value is 1
now, 10

[download]

Notice that $bar got blessed, too, though we didn't do a thing to $bar itself. $baz escaped, having its own thing to point to.

So, we see what bless does. It takes a reference and an identifier string, and marks what the reference points to as an object tagged by the identifier. That identifier is used in looking for methods by checking the symbol table for the tag and looking under it for subs.

After Compline,
Zaxo

In reply to Re: why "Bless" in OO Perl by Zaxo
in thread why "Bless" in OO Perl by Anonymous Monk

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