Hi Joe, Yes, I've noticed that a few languages support it (XPath 1.0 doesn't, though). I'm just questioning the usefulness of this "feature". In my view, simplification is always a good reason to forbid things like these.
-- Santiago ----- Original Message ----- From: "Joseph Kesselman" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Cc: "Scott Boag" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Thursday, February 06, 2003 9:45 AM Subject: Re: user actions > > I wonder what the meaning of "+-++-10" would be? :-) > > That's traditional when writing grammars for math expressions. Unary + is > a no-op, unary - is a negation, and if they're stacked the result is the > same as if parens had been used. In other words, the meaning of the above > is "10" since the two -'s cancel each other -- just as if you'd written > +(-(=(=(-(10))))). > > Almost nobody takes advantage of this... but there seems to be no reason > to forbid it. > > (Remember, this isn't a C-based language, so ++ and -- don't have special > meaning.) > > ______________________________________ > Joe Kesselman / IBM Research >
