The real costs of software rewrites
Does anyone have any hard data on how much it actually costs to rewrite an existing piece of software? I love Joel's article, but it doesn't have any hard data on the subject.
Well, it depends.
In my experience deep refraction - you do not change what the thing is doing but you move a lot of code around to provide meaningful structure and do some substantial clean-ups - should not take more that - 10-15% of developing the whole thing from scratch.
If you just reimplement the same functionality with higher quality, it generally takes about half the time of the original. If you are adding significant functionality, then you have all the standard schedule-making and -keeping problems.
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