如何像 std C++ 流一样使用我的日志记录类? [英] How to use my logging class like a std C++ stream?

问题描述

我有一个工作记录器类，它将一些文本输出到富文本框(Win32，C++)中.问题是，我总是这样使用它:

I've a working logger class, which outputs some text into a richtextbox (Win32, C++). Problem is, i always end up using it like this:

stringstream ss;  
ss << someInt << someString;  
debugLogger.log(ss.str());

相反，像使用流一样使用它会方便得多:

instead, it would be much more convenient to use it like a stream as in:

debugLogger << someInt << someString;

有没有比将所有内容转发到内部字符串流实例更好的方法?如果这样做，我什么时候需要冲洗?

Is there a better way than forwarding everything to an internal stringstream instance? If'd do this, when would i need to flush?

推荐答案

您需要为您的班级适当地实施 operator <<.一般模式如下所示:

You need to implement operator << appropriately for your class. The general pattern looks like this:

template <typename T>
logger& operator <<(logger& log, T const& value) {
    log.your_stringstream << value;
    return log;
}

请注意，这会处理(非const)引用，因为该操作会修改您的记录器.另请注意，您需要返回 log 参数才能使链接正常工作:

Notice that this deals with (non-const) references since the operation modifies your logger. Also notice that you need to return the log parameter in order for chaining to work:

log << 1 << 2 << endl;
// is the same as:
((log << 1) << 2) << endl;

如果最里面的操作没有返回当前的 log 实例，所有其他操作要么在编译时失败(错误的方法签名)要么在运行时被吞没.

If the innermost operation didn't return the current log instance, all other operations would either fail at compile-time (wrong method signature) or would be swallowed at run-time.

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