On Tue, Jul 31, 2012 at 3:03 PM, Coda Highland <chighland@xxxxxxxxx> wrote: > On Tue, Jul 31, 2012 at 3:27 AM, Fjölnir Ásgeirsson > <fjolnir@xxxxxxxxxxxxx> wrote: >> Well no. It pcalls, and catches the error. That can't possibly be as fast as >> just calling dlsym straight. (which is how you check for symbols at runtime >> => I'm not sure what the issue is) > > Mike Pall said just a few e-mails ago that pcall is extremely cheap, > and it's free if it gets JIT-compiled. Look again - he clarified that this is only true if the code getting pcall-ed completes normally (i.e. the first return value of the pcall is true), and not if an error is involved, which is "very expensive on some platforms". -Duncan