插件/提取器操作符覆盖是否可以运行时多态？ [英] Can inserter/extractor operator overrides be made run-time polymorphic?

问题描述

由于这些操作符不能成为成员函数，并且由于朋友函数不能被声明为虚拟，所以我如何制作我的

插入器和提取器多态的？


--Randy Yates

Since these operators can''t be member functions, and since
friend functions can''t be declared virtual, how do I make my
inserters and extractors polymorphic?

--Randy Yates

推荐答案

Randy写道：

由于这些运算符不能成为成员函数，并且由于朋友函数不能被声明为虚拟，我如何使我的
插入器和提取器变为多态？

Since these operators can''t be member functions, and since
friend functions can''t be declared virtual, how do I make my
inserters and extractors polymorphic?

将另一个成员虚拟化并在运营商中调用它<<。


struct Base {

虚拟ostream的和放;输出（ostream&）const = 0;

};


ostream&运算符<< （ostream& os，Base const& b）{

返回b.output（os）;

}


struct Derived ：Base {...


V

Make another member virtual and call it in your operator <<.

struct Base {
virtual ostream& output(ostream&) const = 0;
};

ostream& operator << (ostream& os, Base const& b) {
return b.output(os);
}

struct Derived : Base { ...

V

2006年1月12日11:25:27 -0800，Randy <亚*** @ ieee.org>写道：

On 12 Jan 2006 11:25:27 -0800, "Randy" <ya***@ieee.org> wrote:

由于这些运算符不能成为成员函数，并且由于朋友函数不能被声明为虚拟，我如何使我的
插入器和提取器多态？

Since these operators can''t be member functions, and since
friend functions can''t be declared virtual, how do I make my
inserters and extractors polymorphic?

由运营商超载，例如：


ostream&运营商LT;< （ostream& out，const Base& base）;

ostream&运营商LT;< （ostream& out，const Derived& derived）;

....


祝福，

Roland Pibinger

by operator overloading, eg.

ostream& operator<< (ostream& out, const Base& base);
ostream& operator<< (ostream& out, const Derived& derived);
....

Best wishes,
Roland Pibinger

我明白了。谢谢Victor。


--Randy

I get it. Thanks Victor.

--Randy

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