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Benjamin Mahr
Benjamin Mahr

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Introduction into Logging with Loguru

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This time I would like to give a short introduction into a nice little library I just encountered. It’s called loguru and it’s a lightweight, Thread-Safe, logging library with an impressive good written documentation and human-readable output.

To use it all you need to do is to add a single header and source file to compile with. Unfortunately, that’s, in my opinion, also a drawback. Yes, it’s easier to install and usable in training, but it can’t be exchanged by whoever is operating the system after deployment. In such cases, where the operator wants to define how and what to use for logging, a generic logging interface (facade pattern), such as slf4cxx which is similar to its java pendant slf4j, would be preferable.

Loguru is supporting a various number of features, such as callbacks for logging and fatal errors, verbosity levels, assertions and aborts, and stack traces in case of aborts. It even supports {fmt}. Everyone who ever was used to java/spring log outputs will recognize its similarities.

As you can see it’s pretty straight forward to use. We are not only logging several messages on INFO verbosity level, but also a message in a named thread called “complex lambda”. If we wouldn’t have defined the thread name with loguru::set_thread_name(“complex lambda”), loguru would state the name of a thread with a hex id. The main thread gets its name by calling loguru::init(…). Because our small tool is crashing, loguru is printing us a stack trace which in my opinion is not as helpful as expected, but with ERROR_CONTEXT we get a little better output.

That’s it for now with this post. We have now a short introduction into a, until now, rather unknown, but promising, logging library. Loguru is not only capable of producing Thread-Safe and human readable logging messages but also provides a very simple and handy interface to use.

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Leonardo Furtado