Keith Devens .com - Weblog: New Perl class one-liner

Thursday, August 7, 2003

New Perl class one-liner

You know, I never used to remember all the steps to creating a class in Perl. I always had to look it up, and it's one of those things you don't do very often. The "full" version is something like:

package Classname;

sub new{

    my $class = shift;

    my $self = {};

    bless $self, $class;

    return $self;

}

Well, I realized there's an easy one-liner that's much easier to remember:

package Classname;

sub new{

    return bless {}, shift;

}

If you want to throw data in there, you can:

sub new{

    return bless {foo=>1,bar=>2}, shift;

}

Obviously if you want to call any methods on your object to initialize it you'll have to split that line up, but this gives you an easy-to-remember version that's simple to split up.

Permalink | 7 Comments | Tags: Programming | id 4164

09:03 (utc-4)

Comments

It's still double-dutch to me. I never got the hang of OOP in Perl - I know it's really powerful, but the syntax is just ridiculously obscure. It's painfully obvious that OOP was "tacked on" to the language some time after the initial syntax was designed.

∴ Simon Willison | 7-Aug-2003 9:42am est | http://simon.incutio.com/ | #2654

Yep, Perl didn't get OO until version 5 I think. Or nested data structures, for that matter It'll be real nice in version 6 though.

George Schlossnagle wrote:

The real reason for the long form is to do:

package Classname;
sub new{
    my $self = shift;
    my $class = ref($self) || $self;
$self = {}; # or whatever you want it to be
    return bless $self, $class;
}

This way you can use new not only a a class method, but as a copy constructor as well.

∴ George Schlossnagle | 7-Aug-2003 10:01am est | #2656

M. Bean wrote:

I'm waiting for Perl 6 before I go back to even considering any further Perl development.

∴ M. Bean | 7-Aug-2003 3:36pm est | #2657

Besides simple scripts, I'm with you.

Actually, I've done some pretty gnarly things with PERL. Not like you can't shoot your foot clean off. But I don't go anywhere without having a copy installed. No like, the ActiveState Perl on one's PC is a very nice way to get small to medium jobs done ... whether it is slicing-n-dicing data, or getting content out on the Net.

Could be shortened to ::

package Classname;
sub new { bless {} }

Feel free to post a comment below. Please see my comment policy.

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