Understanding the Four Rules of Simple Design by Cory Haines I like the 4 simple rules, I think he originally got these from Kent Beck. It is easier to keep this system in your mind if it is just a few basic principles. Working Effectively with Legacy Code by Michael Feathers As others also mentioned this. I think this is becoming more important as people transition to new jobs where they have to take on existing software. Having a process to deal with code that lacks documentation and tests is really important.
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