Omitting parens around arguments is fraught with peril. You've just encountered yet another situation where the parser gets "confused".

It's my understanding that the constants created using constant and using functions with the empty prototype are not identical anymore, and that using constant is the recommended method.

In reply to Re: 2*pi*$r -- constant function without prototype by ikegami
in thread 2*pi*$r -- constant function without prototype by ambrus

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