安全调用Lua中已注册的C++函数。

看一下lua_cpcall和lua_pcall。它们两个都允许在c中保护调用lua的函数。如果它们返回一个非负数，则调用失败，并且lua栈只包含错误字符串。在cpcall的情况下，栈不会被修改。对于pcall，您将需要查看lua_pushcclosure来安全地调用cfunction。

你所做的就是：创建一个包含所有你想要的lua_*调用的c函数，例如loadfile和dofile。你使用lua_cpcall或lua_pushcclosure和lua_pcall调用这个函数。这使你能够检测是否在你传递给cpcall的函数中出现错误。

示例：

```` function hello() { string hello_ = "Hello Lua!"; struct C { static int call(lua_State* L) { C *p = static_cast<C*>(lua_touserdata(L,-1)); lua_pushstring(L, p->str.c_str() ); lua_getglobal(L, "print"); lua_call(L, 1, 0); //ok lua_pushstring(L, p->str.c_str() ); lua_getglobal(L, "notprint"); lua_call(L, 1, 0); //error -> longjmps return 0; //Number of values on stack to 'return' to lua } const string& str; } p = { hello_ }; //protected call of C::call() above //with &p as 1st/only element on Lua stack //any errors encountered will trigger a longjmp out of lua and //return a non-0 error code and a string on the stack //A return of 0 indicates success and the stack is unmodified //to invoke LUA functions safely use the lua_pcall function int res = lua_cpcall(L, &C::call, &p); if( res ) { string err = lua_tostring(L, -1); lua_pop(L, 1); //Error hanlder here } //load a .lua file if( (res=luaL_loadfile(L, "myLuaFile.lua")) ) { string err = lua_tostring(L, -1); lua_pop(L, 1); //res is one of //LUA_ERRSYNTAX - Lua syntax error //LUA_ERRMEM - Out of memory error //LUE_ERRFILE - File not found/accessible error } //execute it if( (res=lua_pcall(L,0,0,0)) ) { string err = lua_tostring(L, -1); lua_pop(L, 1); // res is one of // LUA_ERRRUN: a runtime error. // LUA_ERRMEM: memory allocation error. // LUA_ERRERR: error while running the error handler function (NULL in this case). } // try to call [a_int,b_str] = Foo(1,2,"3") lua_getglobal(L,"Foo"); if( lua_isfunction(L,lua_gettop(L)) ) { //Foo exists lua_pushnumber(L,1); lua_pushnumber(L,2); lua_pushstring(L,"3"); lua_pushvalue(L, -4); //copy of foo()

if( (res = lua_pcall(L, 3, 2, 0/*default error func*/)) ) {
  string err = lua_tostring(L, -1);
  lua_pop(L, 1);
  //error: see above
}
int a_int = (int)lua_tointeger(L,-2);
string b_str = lua_tostring(L,-1);
lua_pop(L,2+1); //2 returns, + extra copy of Foo()

} }

```