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Posted by PerlFAQ Server on March 5, 2008, 3:03 am
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This is an excerpt from the latest version perlfaq4.pod, which
comes with the standard Perl distribution. These postings aim to
reduce the number of repeated questions as well as allow the community
to review and update the answers. The latest version of the complete
perlfaq is at http://faq.perl.org .
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4.69: How can I use a reference as a hash key?
(contributed by brian d foy)
Hash keys are strings, so you can't really use a reference as the key.
When you try to do that, perl turns the reference into its stringified
form (for instance, "HASH(0xDEADBEEF)"). From there you can't get back
the reference from the stringified form, at least without doing some
extra work on your own. Also remember that hash keys must be unique, but
two different variables can store the same reference (and those
variables can change later).
The "Tie::RefHash" module, which is distributed with perl, might be what
you want. It handles that extra work.
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