const char *lua_setupvalue (lua_State *L, int funcindex, int n);
Sets the value of a closure's upvalue. It assigns the value at the top of the stack to the upvalue and returns its name. It also pops the value from the stack. Parameters funcindex
and n
are as in the lua_getupvalue
(see lua_getupvalue
).
Returns NULL
(and pops nothing) when the index is greater than the number of upvalues.