Menu
I am a junior software engineer who've been given a task to take over a old system. This system has several problems, based on my preliminary assessment.
How should I go about it to enhance the quality of the system and resolve such issues? I can think of using static code analysis software to resolve any bad coding practice.
However, it can't detect any bad design issues or problems. How should I go about resolving these issues step by step?
596
One should not start refactoring unless he has a clear purpose in mind. Once the purpose has been accomplished, one is done. There is probably not an explicit 10 point check list to tell you when you are done, but most people can determine if they are being productive or just playing.
The most common cause of refactoring problems is not in the code -- it's a lack of proper tools. Refactoring nearly always includes renaming variables and methods, changing method signatures, and moving things around. Trying to make all these changes by hand can easily lead to disaster.
Rule of Three. When you're doing something for the first time, just get it done. When you're doing something similar for the second time, cringe at having to repeat but do the same thing anyway. When you're doing something for the third time, start refactoring.
Get and read Working Effectively With Legacy Code. It deals exactly with this situation.
As others have also advised, for refactoring you need a solid set of unit tests. However, legacy code is typically very difficult to unit test as is, since it has not been written to be unit testable. So you need to refactor first to allow unit testing, which would allow you to start refactoring... a bad catch.
This is where the book will help you. It gives lots of practical advice on how to make badly designed code unit testable with the minimal, and safest possible, code changes. Automatic refactorings can also help you here, but there are tricks described in the book which can only be done by hand. Then once the first set of unit tests are in place, you can start gradually refactoring towards better, more maintainable code.
Update: For hints on how to take over legacy code, you may find this earlier answer of mine useful.
As @Alex noted, unit tests are also very useful to understand and document the actual behaviour of the code. This is especially useful when documentation about the system is nonexistent or outdated.
63
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
