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OT: Rewrite or Refactor?by badaiaqrandista (Pilgrim)
|on Aug 27, 2006 at 02:08 UTC||Need Help??|
I need the wealth of your wisdom and experience in software development, so this is not related to Perl per se. Hence 'OT' in the subject. The software that I've been working on for the past 2.5 years has become so hard to optimise and modified. We had a meeting last week and we decided to re-architect it.
The basic problem is that the software is written as one monolithic mod_perl application, which appears to be three different products to the client. To be able to go forward, we need to do deep surgery on it and split it to different independent sub-systems and layers. We also need to majorly change the database structure. Although we might be able to reuse the existing modules, I am sure that the new architecture will be completely different from now.
This brings me to question, "HOW are we gonna do it?" There are two options: First is to Rewrite, and second is to Refactor. I'll list the good and the bad of each approach from my point of view. Then I'd like to hear what y'all have experienced when facing problems like this.
My definition of Rewrite is to create the new architecture and then copy the relevant modules from the old code base with probably some modifications to fit the module with the new architecture. So this is not a complete rewrite, but this is not a refactoring either.
My definition of Refactor is to change the code one thing at a time, whithout affecting functionality.
I haven't made up my mind on either approach. And due to my limited experience, I can't get a more exhaustive list of the good and the bad of them. Can you help?
UPDATE: Thanks for everyone who've provided their insights. More insights are welcome. Up to this minute the best insight is from GrandFather, which suggested to refactor by creating interfaces and test suites.
UPDATE: Strangler Application pointed by adrianh seems to be the technique that incorporate interfaces mentioned by GrandFather. Great suggestions guys!!! Keep it coming.