Re: Multiple functions: was the gc

[Andrew Teirney <andrew@...>]

D Burgess wrote:
> lua_getfenv() and getfenv() need to handle the case when
> c.env == NULL
>
> Also,  getcurrenv() in lapi.c needs a little thought.

I have attached another patch which i feel is a lot nicer in its 
implementation than the previous 5 minute job i threw together.

The lua_getfenv has been resolved to return nil should the function not 
have an environment. I have removed the lua_clearfenv()/clearfenv() 
functions in favour of using lua_setfenv/setfenv() with nil as the 
special value that indicates the environment should be the "dynamic 
environment". By that meaning use the environment of the current thread 
as opposed to the inherited environment at creation time.

With regards to the getcurrenv(), it does depend on what one wants 
really. My understanding, the lua implementors can correct me if i am 
wrong, but the environments are inherited from the enclosing closure, 
this is for both closures and userdata. If one considers this nil 
environment to be a dynamic environment then it would make sense that 
new objects inherit the dynamic environment, this is represented as no 
environment.

Naturally i cannot guarantee that this works and is bug free ;-)

Andrew



diff -r lua-5.1.1/src/lapi.c lua-5.1.1.patched/src/lapi.c
64c64
<       sethvalue(L, &L->env, func->c.env);
---
>       sethvalue(L, &L->env, func->c.env ? func->c.env : hvalue(gt(L)));
616a617
>   setnilvalue(L->top);
619c620,621
<       sethvalue(L, L->top, clvalue(o)->c.env);
---
>       if (clvalue(o)->c.env)
>         sethvalue(L, L->top, clvalue(o)->c.env);
622c624,625
<       sethvalue(L, L->top, uvalue(o)->env);
---
>       if (uvalue(o)->env)
>         sethvalue(L, L->top, uvalue(o)->env);
627,629d629
<     default:
<       setnilvalue(L->top);
<       break;
737d736
<   api_check(L, ttistable(L->top - 1));
740c739,740
<       clvalue(o)->c.env = hvalue(L->top - 1);
---
>       api_check(L, ttistable(L->top - 1) || ttisnil(L->top - 1));
>       clvalue(o)->c.env = ttisnil(L->top - 1) ? NULL : hvalue(L->top - 1);
742a743
>       api_check(L, ttistable(L->top - 1));
745a747
>       api_check(L, ttistable(L->top - 1));
diff -r lua-5.1.1/src/lbaselib.c lua-5.1.1.patched/src/lbaselib.c
144c144
<   luaL_checktype(L, 2, LUA_TTABLE);
---
>   int t = lua_type(L, 2);
145a146,150
>   if (lua_isfunction(L, -1))
>     luaL_argcheck(L, t == LUA_TNIL || t == LUA_TTABLE, 2,
> 		      "nil or table expected");
>   else
>     luaL_checktype(L, 2, LUA_TTABLE);
diff -r lua-5.1.1/src/lgc.c lua-5.1.1.patched/src/lgc.c
225c225,226
<   markobject(g, cl->c.env);
---
>   if (cl->c.env)
>     markobject(g, cl->c.env);
diff -r lua-5.1.1/src/lvm.c lua-5.1.1.patched/src/lvm.c
433c433
<         Protect(luaV_gettable(L, &g, rb, ra));
---
>         Protect(luaV_gettable(L, cl->env ? &g : gt(L), rb, ra));
444c444
<         Protect(luaV_settable(L, &g, KBx(i), ra));
---
>         Protect(luaV_settable(L, cl->env ? &g : gt(L), KBx(i), ra));