Зачем выполнять этот код:
// DefaultAny.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <iostream>
#include <exception>
using std::cout;
template<class T>
struct NoReturnPolicy
{
static void calculate(T& result, const T& source)
{
result = source;
}
};
template<class T>
struct ReturnPolicy
{
static T& calculate(T& result, const T& source)
{
result = source;
return result;
}
};
template<class T>
struct ThrowPolicy
{
static void check(T* ptr)
{
cout << "ThrowPolicy";
struct Nullptr: public std::exception{};
if(!ptr)
{
throw Nullptr("Nullptr not allowed");
}
}
};
template<class T>
struct NoThrowPolicy
{
static T* check(T* ptr)
{
cout << "NoThrowPolicy";
if(!ptr)
{
return nullptr;
}
else
{
return ptr;
}
}
};
/*
If pointer already points at
something no assignement is being done
*/
template<class T, class ThrowingPolicy>
struct NoAssignPolicy
{
static T* check(T* dest,const T*const src)
{
cout << "NoAssignPolicy";
if (!ThrowPolicy::check(dest))
{
dest = operator new(sizeof(T));
new (dest) T(*src);
}
}
};
template<class T,class ThrowingPolicy>
struct NoCheckPolicy
{
static void check(T* p)
{
cout << "NoCheckPolicy";
}
};
template<class T,class ThrowingPolicy>
struct CheckPolicy
{
static void check(T* p)
{
cout << "CheckPolicy";
ThrowingPolicy::check(p);
}
};
template<
class T,
class ThrowingPolicy = NoThrowPolicy<T>,
class CheckingPolicy = NoCheckPolicy<T,ThrowingPolicy>,
class AssigningPolicy = NoAssignPolicy<T,ThrowingPolicy>,
class ReturningPolicy = NoReturnPolicy<T>
>
struct BreadSlicer
{
BreadSlicer()
{
cout << "Type: " << typeid(T).name() << '\n';
cout << "ThrowingPolicy: " << ThrowingPolicy::check(0) << '\n'; //
//<<<---------The second call to cout makes output on my console:
//NoThrowPolicy:"NoSpace"ThrowingPolicy:"Space"000000
}
};
//The words NoSpace and Space do not actually appear in my console ;) and they are in the opposite order.
int _tmain(int argc, _TCHAR* argv[])
{
BreadSlicer<int> a;
return 0;
}
См. Комментарии в первой структуре выше main.