lua_pushusertag(L,0,my-tag)

[mark@...]

Hello all,

Is there an issue using lua_pushusertag with a reserved tag when the
void* to push is 0?

I am getting some odd behaviour.  I have a gc method attached to all
user data with a given tag and the user data that should have a 0 value
for the pointer allways comes back with a different value.

I have the following lua code

  bounds = anm_boundingrect()
  lens = anm_lens
  null = anm_call(lens,"getBounds",bounds)
  anm_print(null)

anm_* are functions that I have lua_register'd

I know that my anm_call function is returning 0 in this case, and it is
returning 1 to indicate that there is one return value on the lua stack.

In anm_print lua_gettop is returning 1 (as expected).  Then I call
lua_touserdata and I do not get the same value that I pushed in
anm_call, namely 0.  Why not?

I have written many other functions thus far and all is behaving as
expected, this is the only problem I have had.  But I am a first time
lua user so this is all new to me.

For now I am working around the problem by pushing (void*)-1 when I
really mean 0 and then doing a reverse mapping to 0 from -1 when I
should but this is ... um ... ugly.  I haven't found any doc to explain
the behaviour.

Thanks for any insights.

All the best,
Mark.