Perl has a new tied method for that since version 5.8.3: "SCALAR". You couldn't do it before that was added. It now also has heuristics to try to give a good scalar value even if you don't have a SCALAR method. On older perls you can try to make a replacement based on if FIRSTKEY returns something or not (but that implies changing the code that uses the hash in scalar context).

update Older perls returned whatever scalar context would return on the underlying hash that got tied. So if you make sure the hash is not empty before tying, the "if" will always be true, and as explained in a node below, the "while" in your code should then work correctly. So if that kind of use of the hash in scalar context is the only kind happening in your program, that should be a good enough workaround.

In reply to Re: Is it possible to control scalar(%h) when %h is a tied hash? by thospel
in thread Is it possible to control scalar(%h) when %h is a tied hash? by fizbin

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