Couple of points. A cyclic or self-referential structure will break your Tie. Second in the _write sub you are making a _copy_ of the hash. This may or may not be what you want to do.

But I think the heart of your problem is here: 

print FH Data::Dumper->Dump([\%data], ['*data']);

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and here 
my $ret = do $file

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This line sets the $ret value to be equal to the glob *data which was just overwritten by you. (ok, so you ignore the $ret and use the global var \%data, but that was just overwritten so... Same dif.) So its the copy semantics in the _write and _read subs that are causing you trouble. Change them to use scalar refs and not globs and the problem will go away. Oh and lose the shallow copy in _read its misleading and unnecessary.

UPDATE

A question: Why are you mixing proper method calls and procedural calls? _write() is a method, but you call it as a procedure. This means it wont be overidable in a subclass... 

sub DESTROY  { _write ($_[0]) } #not overidable!

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Yves / DeMerphq
---
Writing a good benchmark isnt as easy as it might look.

In reply to Re: Tie-ing hashes clobbers data by demerphq
in thread Tie-ing hashes clobbers data by Dave05

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