如何将木屐重新定义为原始木屐和日志文件? [英] How to redefine clog to tee to original clog and a log file?

问题描述

我在这里看到了一个有用的开始:

I saw a useful start here:

http://www.cs.technion.ac.il/~imaman/programs/teestream.html

制作一个新的流，它可以同时进入堵塞和日志文件.

And it works great to make a new stream which goes to both clog and a log file.

但是，如果我尝试将 clog 重新定义为新流，它将不起作用，因为新流与 clog 具有相同的 rdbuf()，因此以下内容无效:

However, if I try to redefine clog to be the new stream it does not work because the new stream has the same rdbuf() as clog so the following has no effect:

clog.rdbuf(myTee.rdbuf());

那么如何修改 tee 类以拥有自己的 rdbuf()，然后它可以成为 clog 的目标?

So how can I modify the tee class to have its own rdbuf() which can then be the target of clog?

谢谢.

-威廉

推荐答案

如果你真的想继续为 tee 使用 std::clog 而不是将输出发送到不同的流，你需要工作低一级:而不是源自ostream，源自streambuf.然后你可以这样做:

If you really want to keep using std::clog for the tee instead of sending output to a different stream, you need to work one level lower: Instead of deriving from ostream, derive from streambuf. Then you can do this:

fstream logFile(...);
TeeBuf tbuf(logFile.rdbuf(), clog.rdbuf());
clog.rdbuf(&tbuf);

有关如何派生自己的 streambuf 类的更多信息，请参阅 此处.

For more information on how to derive your own streambuf class, see here.

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