in reply to
how to avoid mis-spelling hash keys?
Pre perl 5.8 you can use Tie::Hash::FixedKeys by davorg. It has exactly the functionality you ask for with the drawback of using the tie mechanism which implies a decrease in performance.
By rote learning.
Via Genetic memory.
It's provided by my firmware.
I just remember them.
Thirty days hath September
My computer gets it right, usually.
I just ask someone else.
Someone punches me on the first of the month.
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