FAQ 4.63 Why don't my tied hashes make the defined/exists distinction?

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4.63: Why don't my tied hashes make the defined/exists distinction?

This depends on the tied hash's implementation of EXISTS(). For example,
there isn't the concept of undef with hashes that are tied to DBM*
files. It also means that exists() and defined() do the same thing with
a DBM* file, and what they end up doing is not what they do with
ordinary hashes.



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