Re: Lua 5.1 upvalues

[Anthony Howe <achowe+lua@...>]

On 09/04/2011 00:59, Robert G. Jakabosky whispered from the shadows...:
> That code should be:
> 
> lua_newtable(L);
> lua_pushvalue(L, -1);
> lua_pushcclosure(L, &foobar, 1);
> lua_pushvalue(L, -2);
> lua_pushcclosure(L, &barblat, 1);
> lua_remove(L, -3);

Ok. Thanks.

> Like others have said they can shared the same value, but not the same 'local' 
> storage of that value.  As long as you don't try to store a new value in the 
> upvalue of one C closure and expect the other C closure to see the new value.

I was thinking along those lines, but the above example works too.

The upvalue solution should work for C functions called by Lua that need
a context. I presume that upvalues/C closures are tied the Lua thread state?

> Lua closures can share the same 'local' storage for an upvalue:
> local shared_storage = 123

Q: When loading a Lua script into a master state, do Lua threads a) get
a copy of local variables, b) get their own version of those local
variables (copy by value, not by reference) such that two threads can
have a variable by the same name, but assign different values?

-- 
Anthony C Howe            Skype: SirWumpus                  SnertSoft
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