When to rewrite a code base from scratch

Question

I think back to Joel Spolsky\'s article about never rewriting code from scratch. To sum up his argument: The code doesn\'t get rusty, and while it may not look pretty afte

Answer 1

I have been in precisely this situation but rather than a total rewrite I worked to change things through a refactoring process. The problem I ran into was the enormous complexity of the code I was working with- many pages of horrible, special-case-driven development all based on if-cases and convoluted regexes layered back over about ten years of unplanned growth and expansion.

My aim was to get it refactored function by function so that it would provide the same output for the same inputs but work much more cleanly and smoothly under the bonnet to facilitate future growth and improve performance. The general solution was clean and quick but the fixing job on the code just got more and more difficult and complicated as obscure special-cases in the documents being parsed by the system started to show themselves and my nice clean code would generate output that was just a little too different from what the original did ( this was web pages, so a different amount of whitespace could cause all kinds of layout problems on older IE versions ) in small and obscure ways.

I don't know if the reworked code ever got used- I left the company before it had the chance to be fully integrated- but I doubt it. Why use twenty lines of code when fifteen hundred 'if' statements and three-line regular expressions could do the same job?