FAQ 4.70 How can I use a reference as a hash key?

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4.70: 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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