Rewrites happen more often because most shops use horrible practices. It actually doesn't take long for a codebase to be such a mess that rewriting is the best option. I've seen studies that show the average application is rewritten every four versions.
>What if you could import existing useful COBOL code into your favorite IDE and call it using your favorite language?
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>Perhaps business has only tolerated expensive rewrites because mainstream vendors provided no viable alternative.
Craig Berntson
MCSD, Microsoft .Net MVP, Grape City Community Influencer