diff -urN lua/src/lib/lbaselib.c lua_weakrefs/src/lib/lbaselib.c
--- lua/src/lib/lbaselib.c	Mon Nov 6 22:45:18 2000
+++ lua_weakrefs/src/lib/lbaselib.c	Fri Dec 14 14:55:57 2001
@@ -19,6 +19,11 @@
 
 
 
+typedef struct BaseCtrl {
+ int weakreftag; /* tag for weak reference objects */
+} BaseCtrl;
+
+
 /*
 ** If your system does not support `stderr', redefine this function, or
 ** redefine _ERRORMESSAGE so that it won't need _ALERT.
@@ -430,6 +435,42 @@
 }
 
 
+/*
+** Create and return a weak reference to given object. The weak reference
+** object is an unlocked Lua reference stored as a userdata pointer.
+*/
+static int luaB_weakref (lua_State *L) {
+ BaseCtrl *ctrl = (BaseCtrl *)lua_touserdata(L, -1);
+ lua_pop(L, 1);
+ luaL_arg_check(L, !lua_isnil(L, 1), 1, "non-nil value expected");
+ lua_pushuserdata(L, (void*)lua_ref(L, 0));
+ lua_settag(L, ctrl->weakreftag);
+ return 1;
+}
+
+
+/*
+** When weak reference object is called as a function, dereference and
+** return value.
+*/
+static int weakref_call (lua_State *L) {
+ int r = (int)lua_touserdata(L, 1);
+ int valid = lua_getref(L, r);
+ if (!valid) lua_pushnil(L);
+ return 1;
+}
+
+
+/*
+** When weak reference object goes out of scope, release the reference.
+*/
+static int weakref_collect (lua_State *L) {
+ int r = (int)lua_touserdata(L, 1);
+ lua_unref(L, r);
+ return 0;
+}
+
+
 
 
 /*
@@ -641,11 +682,34 @@
 };
 
 
+static const struct luaL_reg base_funcs_tag[] = {
+ {"weakref", luaB_weakref}
+};
+
+
+static void openwithcontrol (lua_State *L) {
+ BaseCtrl *ctrl = (BaseCtrl *)lua_newuserdata(L, sizeof(BaseCtrl));
+ unsigned int i;
+ ctrl->weakreftag = lua_newtag(L);
+ for (i=0; i<sizeof(base_funcs_tag)/sizeof(base_funcs_tag[0]); i++) { + /* put `ctrl' as upvalue for these functions */ + lua_pushvalue(L, -1); + lua_pushcclosure(L, base_funcs_tag[i].func, 1); + lua_setglobal(L, base_funcs_tag[i].name); + } + lua_pop(L, 1); /* pops `ctrl' from stack */ + lua_pushcfunction(L, weakref_call); + lua_settagmethod(L, ctrl->weakreftag, "function");
+ lua_pushcfunction(L, weakref_collect);
+ lua_settagmethod(L, ctrl->weakreftag, "gc");
+}
+
 
 LUALIB_API void lua_baselibopen (lua_State *L) {
 luaL_openl(L, base_funcs);
 lua_pushstring(L, LUA_VERSION);
 lua_setglobal(L, "_VERSION");
 deprecated_funcs(L);
+ openwithcontrol(L);
 }
 
diff -urN lua/test/weakref.lua lua_weakrefs/test/weakref.lua
--- lua/test/weakref.lua	Thu Jan 1 09:00:00 1970
+++ lua_weakrefs/test/weakref.lua	Fri Dec 14 14:55:57 2001
@@ -0,0 +1,13 @@
+local a_ref
+
+do
+ local a = { }
+ print(a)
+ a_ref = weakref(a)
+ print(a_ref())
+end
+
+-- variable a is now out of scope, force a gc cycle to collect it
+collectgarbage()
+
+print(a_ref())
</div><div class="naked_ctrl">
<form action="/index.cgi/contrast" method="get" name="gate">
<p><a href="http://altstyle.alfasado.net">AltStyle</a> によって変換されたページ <a href="http://lua-users.org/files/wiki_insecure/power_patches/4.0/weakrefs.patch">(-&gt;オリジナル)</a>
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