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scott meyes 代码简单剖析完全修正版 2.0
/*note
请使用g++ 2.95 or higher, intel c++ 5.0 or higher (6.0 has been released)
编译，其他主流编译器无法正确通过, vc 居然出现 26 处错误 */
#include < iostream >
#include < utility > //
含 pair 和 make_pairusing namespace std;
template <typename t>
struct memfunctraits { };
//partial specialization 1
template < typename r, typename o >
struct memfunctraits< r (o::*)() /*
指向成员函数指针 */ > { typedef r returntype;
typedef o objecttype;
};
//partial specialization 2
template < typename r, typename o >
struct memfunctraits< r (o::*)() const /*
指向成员函数 const 的指针 */ > { typedef r returntype;
typedef o objecttype;
};
//partial specialization 3
template < typename r, typename o, typename p1 >
struct memfunctraits< r (o::*)(p1) /*
指向具有参数类型的成员函数指针 */ > { typedef r returntype;
typedef o objecttype;
};
//partial specialization 4
template < typename r, typename o, typename p1 >
struct memfunctraits< r (o::*)(p1) const /*
指向具有参数类型的 const 成员函数指针 */ > { typedef r returntype;
typedef o objecttype;
};
template < typename memfuncptrtype >
class pmfc {
public:
typedef typename memfunctraits<memfuncptrtype>::objecttype objecttype;
typedef typename memfunctraits<memfuncptrtype>::returntype returntype;
typedef std::pair<objecttype*, memfuncptrtype> callinfo;
pmfc(const callinfo& info) : _callinfo(info) { } //init
//
支持无参数类型，returntype = memfuncpretype returntype operator()() const
{ return (_callinfo.first->*_callinfo.second)(); }
// 支持具有参数类型
template <typename param1type>
returntype operator()(param1type p1) const
{ return (_callinfo.first->*_callinfo.second)(p1); }
private:
callinfo _callinfo;
};
template <typename t>
class smartptrbase {
public:
smartptrbase(t *p) : ptr(p) { } //init
//partial specialization pmfc
并 重载 operator->*. template <typename memfuncptrtype>
const pmfc<memfuncptrtype> operator->*(memfuncptrtype pmf) const
{ return std::make_pair(ptr, pmf); }
private:
t* ptr;
};
template <typename t>
class sp : private smartptrbase<t> { // g++ 3.04
都有错误，改为 public，估计是一个 bug。intel c++没有错误。public:
sp(t *p) : smartptrbase<t>(p) { }
using smartptrbase<t>::operator->*;
};
class wombat {
public:
int dig() { cout << "digging..." << endl; return 1; }
int sleep() { cout << "sleeping..." << endl; return 5; }
int eat() const { cout << "eatting..." << endl; return 7; }
int move(int op) { cout << "moving..." << endl; return 9; }
};
typedef int (wombat::*pwmf)();
typedef int (wombat::*pwmfc)() const;
typedef int (wombat::*pwmf1)(int);
main()
{
sp<wombat> pw = new wombat;
pwmf pmf = &wombat::dig;
(pw->*pmf)(); // digging...
pmf = &wombat::sleep;
(pw->*pmf)(); // sleeping...
pwmfc pmfc = &wombat::eat;
(pw->*pmfc)(); // eatting...
pwmf1 pmf1 = &wombat::move;
(pw->*pmf1)(2); // eatting...
return 0;
}
