in reply to Is it possible to control scalar(%h) when %h is a tied hash?

If you're pre-5.8, you could overload KEYS using wantarray to determine context. So, you would do if ( keys %$ref) { ... } and it would do the right thing.

Of course, if your code is exactly like: 

if (%$ref) {
    while ( my ($k, $v) = each %$ref ) {
        ...
    }
}

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You could remove the if-check because the while-loop will never execute; it will encounter a false condition on the first check.

You cannot do this logical refactoring if you have any code before or after the while-loop.

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