> This is very quickly becoming a huge pain for me to write. I have to write a compiler, and a lexer. I have to continue extending this for each new kind of ope

> This is very quickly becoming a huge pain for me to write. I have to write a compiler, and a lexer. I have to continue extending this for each new kind of operator added. Counterpoint: good luck getting that magical regex to scale to many new operators. Or other data types, for that matter. What if, for instance, you wanted to add support for strings? Suddenly, the entire original approach is useless and building a tiny compiler is the best and safest option. It also the case that, as olegbulatov demonstrated, you're fighting an uphill battle trying to sanitize code with a regex. There's really not reasonable way to prove with 100% certainty that a regexp blocks _all possible expressions_ that could do nasty things. Writing a tiny compiler might be a pain in the ass, but you can be very sure of the safety that it offers....and it doesn't need to use eval().