帮助boost绑定/函数 [英] Help with boost bind/functions

问题描述

我有这个函数签名我必须匹配

  typedef int（* lua_CFunction）（lua_State * L） target sig 
  

这里是我到目前为止：

  // somehere else ... 
 ... 
 registerFunction< LuaEngine>（testFunc，& LuaEngine :: testFunc，this）; 
 ... 
 
 // 0 arg callback 
 void funcCallback0（boost :: function< void（）> func，lua_State * state）
 {
 func（）; 
} 
 
 template< typename SelfType> 
 void registerFunction（const std :: string& funcName，boost :: function< void（SelfType *）> func，SelfType * self）
 {
 // funcToCall必须匹配lua_CFunction 
 boost :: function< void（lua_State *）> funcToCall = boost :: bind（& LuaEngine :: funcCallback0，this，
 boost :: bind（func，self），_1）; 
 lua_register（_luaState，funcName.c_str（），funcToCall）;但是，在 lua_register（_luaState ...    / code>，仍然抱怨转换问题
 
 
错误1错误C2664：
'lua_pushcclosure'：无法转换
参数2从
'boost :: function'到
'lua_CFunction'
 
 
如何解决这个问题？
解决方案
这不能直接解决Lua API需要一个简单的函数指针 - 同时， boost :: function 是一个函数对象，没有办法可以转换为一个简单的函数指针，因为 -  - 它不仅捕获代码，而且捕获状态在你的例子中，捕获的状态是 self 的值，因此它有一个代码的代码指针，一些数据 - 而目标API只需要代码指针。
 
I have this function signature I have to match
typedef int (*lua_CFunction) (lua_State *L);//target sig
Here's what I have so far:
    //somewhere else... 
    ...
registerFunction<LuaEngine>("testFunc", &LuaEngine::testFunc, this);
    ...

    //0 arg callback
void funcCallback0(boost::function<void ()> func, lua_State *state)
{
	func();
}

template<typename SelfType>
void registerFunction(const std::string &funcName, boost::function<void (SelfType*)> func, SelfType *self)
{
            //funcToCall has to match lua_CFunction
	boost::function<void (lua_State *)> funcToCall = boost::bind(&LuaEngine::funcCallback0, this,
		boost::bind(func, self), _1);
	lua_register(_luaState, funcName.c_str(), funcToCall);
}
However, at lua_register(_luaState..., it's still complaining about conversion issues 

  
Error 1	error C2664:
  'lua_pushcclosure' : cannot convert
  parameter 2 from
  'boost::function' to
  'lua_CFunction'
Anyone know how this can be solved?
解决方案
This cannot be solved directly. Lua API wants a plain function pointers from you - that's just a code pointer, and nothing else. Meanwhile, boost::function is a function object, and there's no way it could possibly be convertible to a plain function pointer, because - roughly speaking - it captures not just the code, but also the state. In your example, the captured state is the value of self. So it has a code pointer for the code, and some data - and the target API expects just the code pointer.

                        
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