Continuing this exploration of logging solutions used in various projects, let's look at logging in Kohana 3.

While Monolog and log4php share a mostly common logging model of a frontal Logger object instantiated as many times as needed to supply different logging channels, in which log events are Processed/Filtered then written out by Handlers/Writers, Kohana builds upon a simpler model, which can be summarized by three patterns:

• Singleton: there is only one instance of the Kohana Log
• Observer: Log_Writer instances are attached (and detached) to(/from) the logger instance and handle events they are interested in based on their own configuration. Much like a Drupal hook, all writer instances receive each Log event
• Delegation: the Log exposes a write() to trigger the buffered writing, but does not implement it itself, but delegates to the Log_Writer objects to perform it. Buffered logging control is a Log property, not a Log_Writer property.

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