This was discussed previously at Is "ref($class) || $class" a bad thing?

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)

The ref method returns the class name. It will return undef if it's argument is not a ref, in which case the || will give the class name.

In the discussion mentioned above, people debate whether this is good form or not. I tend to say you should not make methods with multiple calling conventions, but Perl is about freedom and many wise programmers disagree with me.

Phil

That extra bit of code there is to get the constructor to work as both an object method and a class method. I.e. it allows the user of the class to write my $newobj = $someobj->new(); or the more familiar  my $newobj = ThisClass->new();. Some people (I'm one) think this isn't really a good idea most of the time.

-sauoq
"My two cents aren't worth a dime.";

use Scalar::Util qw( blessed );

sub new {
    my $class = shift;

    return $class->clone( @_ ) if blessed $class;

    # Continue on with constructor.
}

sub clone {
    my $self = shift;

    return $self->new( @_ ) unless blessed $self;

    # Continue on with cloner.
}
[download]

Otherwise, I document what my methods expect and laugh at the people who don't RTFM.

Ok, that makes sense! But all this can be solved if you do:

package PackageName ;
sub new {
      $class = shift ;
     return bless {}, PackageName ;
}
[download]

This way you don't care if $class is a reference or not!
Luca

This way you don't care if $class is a reference or not!

And you don't allow people to subclass your class.

Plus, if you're going to do that, do it right:

sub new {
    return bless {}, __PACKAGE__;
}
[download]

---

My criteria for good software:

1. Does it work?
2. Can someone else come in, make a change, and be reasonably certain no bugs were introduced?