I am new to Vala programming and have experiences with Java and .NET yet I haven't been able to find anything useful on how to log with Vala. Is there any useful logging facility like log4j or log4net or what's the suggested way to log in Vala with scaling into several logging levels like error, warn, debug and trace? And what about defensive programming like assertions and contracts? Are there any or what's the suggested way to do defensive programming and to get most useful logs with stack traces and precise root cause? Thanks for an advice.

logging vala defensive-programming
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