提升功能模板错误 [英] boost function template error
问题描述
我正在开发一个类来管理一些回调,例如鼠标单击或显示(需要刷新窗口时调用的回调)
I'm developping a class for manage some callbacks such mouse click or display (callback called when window need to be refreshed)
回调和句柄保存在地图中.我正在尝试创建一个可以在地图中注册回调的函数(addCallback).
callbacks and handles are saved in maps. I'm trying to create a function that can register a callback in the maps (addCallback).
class CallBackManager {
public:
enum CallBackType {
DISPLAY = 1 << 0,
MOUSE = 1 << 1
};
template<typename T>
void AddCallback(CallBackType type, int hwnd, T f) {
if (type & DISPLAY) {
addDisplayCallback(hwnd, f); // 50 lines of error here
}
if (type & MOUSE) {
addMouseCallback(hwnd, f); // The same here
}
}
private:
void addDisplayCallback(int hwnd, boost::function<void ()> f) {
_display_callback[hwnd] = f;
};
void addMouseCallback(int hwnd, boost::function<void (int, int)> f) {
_mouse_callback[hwnd] = f;
};
std::map<int, boost::function<void ()>> _display_callback;
std::map<int, boost::function<void (int, int)>> _mouse_callback;
};
我这样称呼那些功能:
CallBackManager cbm;
cbm.AddCallBack(
CallBackManager::CallBackType::DISPLAY,
my_handle,
boost::bind(&Foo::Display, this)); // boost::function<void ()>
cbm.AddCallback(
CallBackManager::CallBackType::DISPLAY,
my_handle,
boost::bind(&Foo::Mouse, this, _1, _2)): //boost::function<void (int, int)>
最后错误是:
error C2784: 'T &boost::_bi::list0::operator [](const boost::reference_wrapper<T> &) const' : could not deduce template argument C:\local\boost_1_57_0_b1\boost\bind\bind.hpp 392
我不明白此错误
(这是带有编译错误的代码) https://ideone.com/BdW1Ln
(here is the code with the compilation error) https://ideone.com/BdW1Ln
推荐答案
您要在同一静态代码路径中将T
类型的函数添加到两个映射中.当然,您可以对其进行过滤,但这就是运行时.这行不通.
You're adding the function of T
type to both maps, in the same static code path. Of course, you filter it, but that's runtime. This can't work.
只需使用单独的功能.
它更短,更易读.
Live On Coliru
#include <boost/function.hpp>
#include <boost/bind.hpp>
#include <map>
class CallBackManager {
public:
enum CallBackType { DISPLAY = 1 << 0, MOUSE = 1 << 1 };
struct display_callback_t;
template <typename F>
void AddDisplayCallback(int hwnd, F f) {
addDisplayCallback(hwnd, f);
}
template <typename F>
void AddMouseCallback(int hwnd, F f) {
addMouseCallback(hwnd, f);
}
void test() {
for (auto& f : _display_callback)
f.second();
for (auto& f : _mouse_callback)
f.second(rand(), rand());
}
private:
void addDisplayCallback(int hwnd, boost::function<void()> f) { _display_callback[hwnd] = f; };
void addMouseCallback(int hwnd, boost::function<void(int, int)> f) { _mouse_callback[hwnd] = f; };
std::map<int, boost::function<void()>> _display_callback;
std::map<int, boost::function<void(int, int)>> _mouse_callback;
};
#include <iostream>
struct Foo {
int my_handle;
CallBackManager cbm;
Foo()
{
cbm.AddDisplayCallback(my_handle, boost::bind(&Foo::Display, this));
cbm.AddMouseCallback(my_handle, boost::bind(&Foo::Mouse, this, _1, _2));
}
void Mouse(int, int) {
std::cout << __PRETTY_FUNCTION__ << "\n";
}
void Display() {
std::cout << __PRETTY_FUNCTION__ << "\n";
}
};
int main() {
Foo instance;
instance.cbm.test();
}
打印
void Foo::Display()
void Foo::Mouse(int, int)
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