use l2kashe 'new';
my $o = new;
$o->foo( ... );
# Vs
use l2kashe;
my $o = l2kashe->new;
$o->foo( ... );

##</code><code>##

use l2kashe; # The importing new() dies
sub new { ... } # This one stays
# Vs
sub new { ... } # The original new() dies
use l2kashe; # This one overwrites

##</code><code>##

sub new { bless {}, shift }
# Vs
sub new { bless {}, __PACKAGE__}
# or maybe even:
sub new { bless {}, 'l2kashe' }

##</code><code>##

sub new {
    my $class_or_parameter = shift;
    if ( $class ne __PACKAGE__ ) {
        unshift @_, $class_or_package;
    }
    bless { @_ }, __PACKAGE__;
}

##</code><code>##

sub something {
    my $self_or_parameter = shift;
    if ( ref $self_or_parameter eq __PACKAGE__ ) {
        unshift @_, $self_or_parameter;
    }
     ...
}