Log4r

Log4r is a software library that was written in Ruby and is suitable for use in any Ruby program. It is free and open-source, meaning that anyone can use it and adjust its source code to fit their needs. Log4r has a flexible and comprehensive logging system that features several levels, custom level names, logger inheritance, multiple output destinations, execution tracing, custom formatting, thread safety, XML, and YAML configuration, among others.

The hierarchical logging system in Log4r allows the user to create any number of levels and customize the names to fit their needs. Additionally, Log4r allows information to be sent to any type of destination and with varying degrees of importance. Log4r adheres to a philosophy of logging using simple print statements but adds the ability to control the information being logged in a flexible way.

Log4r is designed to have almost no extra computational cost in production code, and the library is easy to use and configure for all levels of complexity. Casual scripts can use Log4r right away with minimal configuration, and more sophisticated applications can set up a structured configuration file in XML or YAML. The library provides comprehensive documentation, including a user manual, a reference API, and over a dozen examples.

Log4r aims to abide by the Principle of Least Surprise, working as intended at all points. Overall, Log4r is an excellent software library for logging purposes, with a range of features that make it an excellent choice for any Ruby programmer.