basho/lager — pull request #71 by fenek (2012-08-24 08:17:53+00:00)
Title: Custom loglevels aka per module loglevels

My current task at work is to integrate our ejabberd fork with lager and I needed to modify lager so it could provide exactly the same functionality as ejabberd's set_custom function. Tracing feature was not enough as it allowed me only to "lower" loglevel of specific module but I couldn't make it higher than global backend loglevel.
I didn't want to modify existing behaviour of tracing so I added a feature on top of existing solution, which may be some duplicate of tracing functionality but is easier to use and allows to make module loglevel higher.