Think of it this way. When you call a method,

$object->method( 1, 2, 3 );
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What perl does is

1. Inspects $object, which is a blessed reference of some kind, and finds out the package that it was blessed into.

   You can see this yourself if you print a blessed reference and you get something like  My::Package=HASH(0x1d154d8). In this case $object is a hashref that was blessed into the package My::Package.

2. It then looks up the address of the sub named 'method' in the package My::Package, and then calls that address passing the list $object, 1, 2, 3 in @_.

   Hence, the first thing you shift off @_ within the method is $self. Ie. The object upon which the method was called.

However, when you take the address of a method

my $codref = \&$object->method;
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and then later invoke it (or have the parser invoke for you),

$coderef->( 1, 2, 3 );
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Perl no longer recognises that you are invoking a method rather than a function, and therefore doesn't add $object to the stack. Even if it knew that this was a method call, it no longer knows which package (or which instance of that package) was used to derive the address of the method. So it wouldn't know what $object to pass.

Indirecting the call through a closure simply allows you to retain the instance handle along with the method to be invoked, with the slight penalty of the two step process of getting there.

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Examine what is said, not who speaks.

"Efficiency is intelligent laziness." -David Dunham
"When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong." -Richard Buckminster Fuller

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