如何从 std::ostream 继承? [英] How to inherit from std::ostream?

问题描述

我一直在谷歌搜索，但找不到简单的答案.它应该很简单，就像 STL 一样.

I've been googling around and I just can't find a simple answer to this. And it should be simple, as the STL generally is.

我想定义从 std::ostream 公开继承的 MyOStream.假设每次有内容写入我的流时，我都想调用 foo().

I want to define MyOStream which inherits publicly from std::ostream. Let's say I want to call foo() each time something is written into my stream.

class MyOStream : public ostream {
public:
  ...
private:
   void foo() { ... }
}

我知道ostream的公共接口是非虚拟的，那怎么做呢?我希望客户能够同时使用 operator<<并在 MyOStream 上 write() 和 put() 并使用了我的类的扩展能力.

I understand that the public interface of ostream is non-virtual, so how can it be done? I want clients to be able to use both operator<< and write() and put() on MyOStream and have use the extended ability of my class.

推荐答案

不幸的是，这不是一个简单的问题.您应该从中派生的类是 basic_ 类，例如 basic_ostream.然而，从一个流派生可能不是你想要的，你可能想从一个流缓冲区派生，然后使用这个类来实例化一个现有的流类.

It's not a simple question, unfortunately. The classes you should derive from are the basic_ classes, such as basic_ostream. However, derivation from a stream may not be what you want, you may want to derive from a stream buffer instead, and then use this class to instantiate an existing stream class.

整个领域都很复杂，但有一本关于它的好书标准 C++ IOStreams 和语言环境，我建议你在继续之前先看看.

The whole area is complex, but there is an excellent book about it Standard C++ IOStreams and Locales, which I suggest you take a look at before going any further.

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