Re: simplest way to trap error in lua?

[Rici Lake <lua@...>]

On 25-Jan-07, at 12:22 AM, Matthew Armstrong wrote:

> Giving a simple example:
>
> function f1()
>     local ohNoImNil = nil
>     ohNoImNil()
> end
>
> function f2()
>     f1()
> end
>
> f2()
>
> What's the easiest way to trap the nil call and dump the stack?
>
> easiest within lua?

> function f1()
>>     local ohNoImNil = nil
>>     ohNoImNil()
>> end
>
> function f2()
>>     f1()
>> end
>

> ok, err =  xpcall(f2, debug.traceback)
> =ok
false
> =err
stdin:3: attempt to call local 'ohNoImNil' (a nil value)
stack traceback:
        stdin:3: in function 'f1'
        stdin:2: in function <stdin:1>
        [C]: in function 'xpcall'
        stdin:1: in main chunk
        [C]: ?

> easiest within c?

lua_pcall(), having put debug.traceback on the stack somewhere and 
providing it's index as the fourth argument.