You should always use the two argument form.

package Widget;
use strict;
use warnings;

sub new {
    my ( $class, @args ) = ( shift, @_ ); 
    my $self = {};
    bless( $self, $class );
}
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I shall anticipate your next question: But $class is the current package, right? So isn't this the same as a one argument bless?

No, it's different. Consider:

{
    package Widget::Special;
    use parent 'Widget';
    
    # We don't write a sub called `new` and rely on the parent class f
+or that.
}

my $special = Widget::Special->new;
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Now $class is "Widget::Special", so the two-argument form of bless does the right thing. The one-argument form of bless would return a plain "Widget" object from Widget::Special->new.

Always, always, always use the two-argument form of bless. One-argument bless needs to go and painfully die in a stinking hole of rancid rotting trash.

I hope that helps. :)