Unless you want to mess around with the internals, I don't see how this is possible.

However it is possible to achieve the same effect by having your tie method accept an optional reference which will have the value stored, and then export utility methods that use it. So you might wind up with something like this interface: 

promise(\ my $result_of_long_compute, sub {
  # Long computation here
});

[download]
and then you implement this along the following lines: 
sub promise {
  my ($to_tie, $implement, $opts);
  if (UNIVERSAL::isa($to_tie, 'SCALAR')) {
    tie $$to_tie, Data::Lazy, $implement, $opts;
  }
  elsif (UNIVERSAL::isa($to_tie, 'HASH')) {
    ...
}

[download]
And then document that using the promise() utility function is faster than using the tie interface.

In reply to Re: How to untie oneself? by tilly
in thread How to untie oneself? by Jenda

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