|Do you know where your variables are?|
Good catch. This is precisely the article I had in mind. Yes, I unashamedly think that rewriting from scratch is the wrong kind of laziness.
Take a look at File::Find sometime. What a mess. My refactored version passes all of the tests (at least on a Unixy system) and is *half* the code of the original. How long would have it taken to rewrite that from scratch? Far longer than it took to make incremental changes and get it into a better working order. (If anyone's interested and can debug on a different platform, let me know.)
Mozilla's a great example. Also consider Perl 6. It's been a year and a couple of months, and with all of the brilliant ideas and hard work and smart people, we've got a handful of design documents, a virtual machine that does some math and can print things out, and (admittedly) saner bytecode. This, while we're still fixing bugs and trying to finish the test suite for Perl 5! Do the internals need to be improved? Yeah. Will Perl 6 deliver? Undoubtedly. Why throw away 35 megabytes of source code if Perl 6 will act 95% the same as Perl 5?
Realistically speaking, if you don't have design documents or tests or even a good idea of what the software is doing, how confident can you be that your rewrite will do what it's supposed to do, at the same level? (If it's not working period, that's a different story.)
And, yeah, your process sure smells a lot like "improving the design of existing code." I don't know of any Refactoring gurus who'd claim that you should have x% of the original code left when you're done refactoring.
My point (and maybe Joel would agree) is that though maintenance isn't the fun part of programming, you very rarely have (or should take) the luxury of skipping it.
Ovid, you'll have to write tests sometime. My recommendation is to do it now, based on the old code. You'll get a handle for what it's really supposed to be doing, you'll immediately see how to fix it, and you'll grow as a programmer very quickly.
In reply to Re: Re (tilly) 1: (OT) Rewriting, from scratch, a huge code base