Programming Perl, 4th Edition

bless

bless REF, CLASSNAME
bless REF

This function tells the referent pointed to by reference REF that it is now an object in the CLASSNAME package—or the current package if no CLASSNAME is specified. If REF is not a valid reference, an exception is raised. For convenience, bless returns the reference, since it’s often the last function in a constructor subroutine. For example:

$pet = Beast–>new(TYPE => "cougar", NAME => "Clyde");

# then in Beast.pm:
sub new {
    my $class  = shift;
    my %attrs = @_;
    my $self   = { %attrs };
    return bless($self, $class);
}

You should generally bless objects into CLASSNAMEs that are mixed case. Namespaces with all lowercase names are reserved for internal use as Perl pragmata (compiler directives). Built-in types (such as “SCALAR”, “ARRAY”, “HASH”, “UNIVERSAL”, etc.) all have uppercase names, so you may wish to avoid such package names as well.

Make sure that CLASSNAME is not false; blessing into false packages is not supported and may result in unpredictable behavior.

It is not a bug that there is no corresponding curse operator. (But there is a sin operator.) See also Chapter 12 for more about the blessing (and blessings) of objects.