C++重载变量参数的运算符逗号

Question

是否可以通过重载参数的运算符逗号来为函数构造可变参数？我想看一个如何做的例子......,也许是这样的:

template <typename T> class ArgList {
public:
    ArgList(const T& a);
    ArgList<T>& operator,(const T& a,const T& b);
}
//declaration
void myFunction(ArgList<int> list);

//in use:
myFunction(1,2,3,4);

//or maybe:
myFunction(ArgList<int>(1),2,3,4);

Answer 1

它有点可能,但用法看起来不太好.例如:

#include <vector>
#include <iostream>
#include <algorithm>
#include <iterator>

template <class T>
class list_of
{
    std::vector<T> data;
public:
    typedef typename std::vector<T>::const_iterator const_iterator;
    const_iterator begin() const { return data.begin(); }
    const_iterator end() const { return data.end(); }

    list_of& operator, (const T& t) {
        data.push_back(t);
        return *this;
    }
};

void print(const list_of<int>& args)
{
    std::copy(args.begin(), args.end(), std::ostream_iterator<int>(std::cout, " "));
}

int main()
{
    print( (list_of<int>(), 1, 2, 3, 4, 5) );
}

这个缺点将在C++ 0x中修复,你可以这样做:

void print(const std::initializer_list<int>& args)
{
    std::copy(args.begin(), args.end(), std::ostream_iterator<int>(std::cout, " "));
}

int main()
{
    print( {1, 2, 3, 4, 5} );
}

甚至是混合类型:

template <class T>
void print(const T& t)
{
    std::cout << t;
}

template <class Arg1, class ...ArgN>
void print(const Arg1& a1, const ArgN& ...an)
{
    std::cout << a1 << ' ';
    print(an...);
}


int main()
{
    print( 1, 2.4, 'u', "hello world" );
}