Re: simplest way to trap error in lua?

[Rici Lake <lua@...>]

On 25-Jan-07, at 3:19 PM, Matthew Armstrong wrote:

> Is there any significant performance overhead when running in 
> protected mode?

No. Setting up the pcall requires one call to setjmp() which creates a 
jump buffer; essentially a snapshot of all the registers and other bits 
of state. Once that's done, execution is normal.

Experiments in C have convinced me that setjmp/longjmp exception 
handling is quite reasonable, and often outperforms c++ exceptions. 
However, you don't want to do it on every call (both for efficiency and 
logic reasons). Put pcall's only in places where you can do something 
about an exceptional condition; if all you're going to do is log the 
error and terminate the computation, for example, you only need one 
outermost pcall.