Re: C extension and stack cleanup on error

["Kacper Wysocki" <kacperw@...>]

On 7/10/07, David Welch <david.welch@thorcom.co.uk> wrote:
> Hi,
>
> I am trying to write a C extension to lua and I am wondering what the
> rules are when it comes to stack cleanup.
[snip code]
> So this function is effectively type checking a tables field and
> returning its value.  If the field doesn't exist then an error
> is raised and a nil value is left on the stack.  If the field is there
> but checkudata fails, once again a value is left on the stack.
>
> What actually happens to the value left on the stack?  Can I basically
> just forget about it?

error() (and luaL_check*() calls error()) unwinds the stack for you so
you don't have to worry about it. It's when there is no error() that
you should pay attention to your stack.

_K