自定义流到C ++中的方法？ [英] Custom stream to method in C++?

问题描述

我正在做一个记录器，我希望有一些流类似的事情发生，理想情况下做 CLogger< 测试，< 1<< ，2,3\\\
; 而不是 CLogger-> log（Testing，％i，2,3，1）;

I'm making a logger and I wish to have some kind of stream-like happenings going on, ideally doing CLogger << "Testing, " << 1 << ",2,3\n"; instead of CLogger->log("Testing, %i,2,3", 1);

我的问题是我该怎么做？我不想直接创建一个流到stdout，因为我想使用我自己的方法，其中包括写入文件等。我考虑过重载一个特定的结构，将冲洗当前流缓冲区一个方法，但我必须做 CLogger<<冲洗

My question is how would I do this? I don't want to directly create a stream to stdout as I want to use my own method which includes writing files and such. I've considered overloading with a certain struct that'd flush the current stream buffer to a method, but I'd have to do CLogger << flush << "Test!\n"; which is kind of odd.

有没有人知道怎么做？

推荐答案

如果你需要的是将某些日志消息定向到文件，你是否考虑过 std :: ofstream

If all that you need is directing certain log messages to files, have you considered std::ofstream?

否则，我喜欢从 std :: ostream 派生我的日志类，的流良好。诀窍是将所有应用程序特定的代码放在相关的streambuf类中。考虑：

Otherwise, I like to derive my logging class from std::ostream, so I get all of the stream goodness. The trick is to put all of your application-specific code in the associated streambuf class. Consider:

#include <iostream>
#include <sstream>

class CLogger : public std::ostream {
private:
    class CLogBuf : public std::stringbuf {
    private:
        // or whatever you need for your application
        std::string m_marker;
    public:
        CLogBuf(const std::string& marker) : m_marker(marker) { }
        ~CLogBuf() {  pubsync(); }
        int sync() {
            std::cout << m_marker << ": " << str();
            str("");
            return std::cout?0:-1;
        }

    };

public:
    // Other constructors could specify filename, etc
    // just remember to pass whatever you need to CLogBuf
    CLogger(const std::string& marker) : std::ostream(new CLogBuf(marker)) {}
    ~CLogger() { delete rdbuf(); }
};

int main()
{
    CLogger hi("hello");
    CLogger bye("goodbye");

    hi << "hello, world" << std::endl;
    hi << "Oops, forgot to flush.\n";
    bye << "goodbye, cruel world\n" << std::flush;
    bye << "Cough, cough.\n";
}

注意：

• CLogger构造函数可以接受您需要使用的任何参数 - 文件名，输出语言，指向底层日志数据的指针。

在响应std :: flush时会自动调用CLogBuf的sync（）。

• The CLogger constructor can take whatever parameters you need to use -- a filename, an output language, a pointer to the underlying log data, whatever. Just pass the data onto the CLogBuf class.
• The CLogBuf's sync() is automatically called during in response to std::flush.

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