Lua - is xpcall as slow as Try...Catch in other languages?

Question

I cant seem to find any info about this on the web, but what are the performance implications of using xpcall vs calling a function directly in lua:

a) When there are no errors?

b) When an error occurs?

Is it similar to try... catch from other languages where handling an exception can cause performances issues?

Answer 1

Languages where the cost of exception handling is talked about, like C++, are those which are intended for high performance in the general case, since cleaning up from an exception involves a tricky and expensive stack-unwinding process, compared to just popping the stack and returning. Lua is a bytecode-interpreted language, and explicitly stores the data needed for that unwinding on its (virtual) stack. So it's a little bit slower than not doing protected calling, but honestly, if you are worried about micro-optimizations like that then you are using the wrong language.