Method: Lua::State#__set_metatable

Defined in:
ext/rlua.c

#__set_metatable=(object, metatable) ⇒ Object

Sets metatable for any valid Lua object. metatable can be Lua::Table or Hash. If you want to set metatables for non-table objects (e.g. numbers) just pass their Ruby equivalent.

# Implement concatenation operator for Lua strnigs.
state = Lua::State.new
state.__set_metatable("", { '__add' => lambda{ |a, b| a + b } })
p state.__eval('return "hello," + " world"') # => "hello, world"


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# File 'ext/rlua.c', line 761

static VALUE rbLua_set_metatable(VALUE self, VALUE object, VALUE metatable)
{
  lua_State* state;
  Data_Get_Struct(rb_iv_get(self, "@state"), lua_State, state);
  
  if(rb_obj_class(metatable) != cLuaTable && TYPE(metatable) != T_HASH)
    rb_raise(rb_eTypeError, "wrong argument type %s (expected Lua::Table or Hash)", rb_obj_classname(metatable));

  rlua_push_var(state, object);                    // stack: |objt|...
  rlua_push_var(state, metatable);                 //        |meta|objt|...
  lua_setmetatable(state, -2);                     //        |objt|...
  lua_pop(state, 1);                               //        ...
  
  return metatable;
}