将 std::cout 重定向到自定义编写器

2022-01-07 00:00:00 stream iostream c++ streambuf stringstream

我想使用 Mr-Edd 的 iostreams 文章中的这个片段在某处打印 std::clog.

I want to use this snippet from Mr-Edd's iostreams article to print std::clog somewhere.

#include <iostream>
#include <iomanip>
#include <string>
#include <sstream>

int main()
{
    std::ostringstream oss;

    // Make clog use the buffer from oss
    std::streambuf *former_buff =
        std::clog.rdbuf(oss.rdbuf());

    std::clog << "This will appear in oss!" << std::flush;

    std::cout << oss.str() << '\n';

    // Give clog back its previous buffer
    std::clog.rdbuf(former_buff);

    return 0;
}

所以，在主循环中，我会做类似

so, in a mainloop, I will do something like 

while (! oss.eof())
{
    //add to window text somewhere
}

这是 ostringstream 文档，但我无法理解最好的方法来做到这一点.我有一个显示文本的方法，我只想用 ostringstream 中的任何数据调用它.

Here's the ostringstream docs but I'm having trouble understanding the best way to do this. I have a method that displays the text, I just want to call it with any data in the ostringstream.

将发送到 std::clog 的任何内容重定向到我选择的方法的最简单/最好的方法是什么?是如上所述，并填写 while !eof 部分(不确定如何)，还是有更好的方法，例如通过在某处重载一些调用我的方法的提交"运算符?我正在寻找快速和简单的方法，我真的不想开始定义接收器，例如文章中所做的使用 boost iostreams 之类的东西 - 这些东西太让我费解了.

What is the easiest/best way to get anything sent to std::clog redirected to a method of my choice? is it as above, and fill in the while !eof part (not sure how), or is there a better way, say by overloading some 'commit' operator somewhere that calls my method? I'm loking for quick and easy, I really don't want to start defining sinks and such with boost iostreams as the article does - that stuff is way over my head.

推荐答案

我鼓励您查看 Boost.IOStreams.它似乎非常适合您的用例，而且使用起来非常简单:

I encourage you to look at Boost.IOStreams. It seems to fit your use-case nicely, and using it is surprisingly simple:

#include <boost/iostreams/concepts.hpp> 
#include <boost/iostreams/stream_buffer.hpp>
#include <iostream>

namespace bio = boost::iostreams;

class MySink : public bio::sink
{
public:
    std::streamsize write(const char* s, std::streamsize n)
    {
        //Do whatever you want with s
        //...
        return n;
    }
};

int main()
{
    bio::stream_buffer<MySink> sb;
    sb.open(MySink());
    std::streambuf * oldbuf = std::clog.rdbuf(&sb);
    std::clog << "hello, world" << std::endl;
    std::clog.rdbuf(oldbuf);
    return 0;
}

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