Re: recursively traverse globals table from C API

[Rici Lake <lua@...>]

On 19-Jan-07, at 9:31 PM, Jérôme VUARAND wrote:

> 2007/1/19, Raymond Jacobs <raymondj@gmail.com>:
> > int idx=LUA_GLOBALSINDEX;
> > lua_getfenv(l,idx);
> >
> > while(lua_next(l,idx)!=0)
> > {
> >                 const char* key=lua_tostring(l,-2);
> >
> >                 //get value at -1 index and check type of it
> >
> >                 //do somthing with key and value based on type of 
> > value
> >                 //if value is a table call this function again to 
> > traverse it, then
> > continue here
> >
> >
> >                 lua_pop(l,1);
> > }
>
> You forget to push an initial nil on the stack before entering you
> while loop (see lua_next documentation example).

He did push a nil, although I suspect it was not by design:

> > int idx=LUA_GLOBALSINDEX;
> > lua_getfenv(l,idx);

Since tables don't have environments, lua_getfenv() will do the job.

By the way, be careful with recursively enumerating tables; if there's 
a circular reference, you'll find yourself running off the end of the C 
stack. (And, since _G._G == _G, there is such a circular reference in 
the standard globals table.)