[OpenSIPS-Devel] [opensips] Mathops extension (#144)
Stéphane Alnet
notifications at github.com
Sat Nov 30 15:34:58 CET 2013
Thank you for your comments.
> Reverse Polish notation is hideous.
YMMV. :) As an HP (RPN) user and someone who has written a Forth interpreter in his formative years, I don't have issues moving between RPN and infix. I saw a RPN evaluator, I needed to add a function to it, it was faster to write a parser for RPN than try to extend and fix the existing parser (accounting for arity, LR(1) parsing, etc.). I understand not everyone will find `math_rpn` attractive or useful.
On a practical (rather than aesthetic) point, the extensions to the evaluator still make sense (but they are missing parsing in `math_eval`), and `math_rpn` is a good way to write unit tests (from an OpenSIPS script) for the individual functions and the evaluator itself.
> `math_rpn("2 1 1 +*", "$var(res)")`
I made the choice (same as in Forth) of using blank-separated words. So you'd effectively have to write this `math_rpn("2 1 1 + *", "$var(res)")`.
I'll revise for code formatting.
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https://github.com/OpenSIPS/opensips/pull/144#issuecomment-29553364
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