自參照用戶數據和垃圾收集

Question

因爲我的用戶數據對象引用自己，我需要刪除和零垃圾收集工作的一個變量。

Lua代碼：

obj = object:new() 
-- 
-- Some time later 
obj:delete() -- Removes the self reference 
obj = nil  -- Ready for collection 

C代碼：

typedef struct { 
    int self; // Reference to the object 
    int callback; // Reference to a Lua function 
    // Other members and function references removed 
} Object; 

// Called from Lua to create a new object 
static int object_new(lua_State *L) { 
    Object *obj = lua_newuserdata(L, sizeof(Object)); 

    // Create the 'self' reference, userdata is on the stack top 
    obj->self = luaL_ref(L, LUA_REGISTRYINDEX); 

    // Put the userdata back on the stack before returning 
    lua_rawgeti(L, LUA_REGISTRYINDEX, obj->self); 

    // The object pointer is also stored outside of Lua for processing in C 

    return 1; 
} 

// Called by Lua to delete an object 
static int object_delete(lua_State *L) { 
    Object *obj = lua_touserdata(L, 1); 

    // Remove the objects self reference 
    luaL_unref(L, LUA_REGISTRYINDEX, obj->self); 

    return 0; 
} 

// Called from Lua to set a callback function 
static int object_set_callback(lua_State *L) { 
    Object *obj = lua_touserdata(L, 1); 

    // Unref an existing callbacks 
    if (obj->callback != 0) { 
     luaL_unref(L, LUA_REGISTRYINDEX, obj->callback); 
     obj->callback = 0; 
    } 

    // Set the new callback - function is on top of the stack 
    obj->callback = luaL_ref(L, LUA_REGISTRYINDEX); 
} 

// Called from C to call a Lua function for the obj 
static void do_callback(Object *obj) { 
    // Push the Lua function onto the stack 
    lua_rawgeti(L, LUA_REGISTRYINDEX, obj->callback); 

    // Push the userdata onto the stack 
    lua_rawgeti(L, LUA_REGISTRYINDEX, obj->self); 

    // Call the function 
    lua_call(L, 1, 0); 
} 

有一些方法我可以設置對象在Lua爲零，並有自動調用了delete（）方法？或者，刪除方法是否可以刪除引用該對象的所有變量？自我參照能力是否「虛弱」？

編輯1：我已經包含代碼，說明爲什麼對象引用本身;請參閱do_callback函數。每個對象都是樹狀結構的一部分，其中大部分處理是用C完成的，但用戶可以設置在某些條件下調用的自定義Lua函數。

編輯2：想到另一種可能的解決方案;而不是每個obj保持對自身的引用，當我需要將它的地址作爲關鍵字傳遞給Lua時，我可以在全局索引中查找對象嗎？

Answer 1

您可以嘗試在註冊表中創建一個弱表並將您的引用存儲在那裏，這樣將您的對象的所有引用設置爲零應該使其可用於gc。