One reason people are tempted to rewrite their entire code base from scratch is that the original code base wasn't designed for what it's doing. It was designed as a prototype, an experiment, a learning exercise, a way to go from zero to IPO in nine months, or a one-off demo. And now it has grown into a big mess that's fragile and impossible to add code to, and everybody's whiny, and the old programmers quit in despair and the new ones that are brought in can't make head or tail of the code so they somehow convince management to give up and start over while Microsoft takes over their business. Today let me tell you a story about what they could have done instead.
FogBUGZ started out six years ago as an experiment to teach myself ASP programming. Pretty soon it became an in-house bug tracking system. It got embellished almost daily with features that people needed until it was good enough that it no longer justified any more work.
Various friends asked me if they could use FogBUGZ at their companies. The trouble was, it had too many hardcoded things that made it a pain to run anywhere other than on the original computer where it was deployed. I had used a bunch of SQL Server stored procedures, which meant that you needed SQL Server to run FogBUGZ, which was expensive and overkill for some of the two person teams that wanted to run it. And so on. So I would tell my friends, "gosh, for $5000 in consulting fees, I'll spend a couple of days and clean up the code so you can run it on your server using Access instead of SQL Server." Generally, my friends thought this was too expensive.
After this happened a few times I had a revelation -- if I could sell the same program to, say, three people, I could charge $2000 and come out ahead. Or thirty people for $200. Software is neat like that. So in late 2000, Michael sat down, ported the code so that it worked on Access or SQL Server, pulled all the site-specific stuff out into a header file, and we started selling the thing. I didn't really expect much to come of it.
In those days, I thought, golly, there are zillions of bug tracking packages out there. Every programmer has written a dinky bug tracking package. Why would anyone buy ours? I knew one thing: programmers who start businesses often have the bad habit of thinking everybody else is a programmer just like them and wants the same stuff as them, and so they have an unhealthy tendency to start businesses that sell programming tools. That's why you see so many scrawny companies hawking source-code-generating geegaws, error catching and emailing geegaws, debugging geegaws, syntax-coloring editing tchotchkes, ftping baubles, and, ahem, bug tracking packages. All kinds of stuff that only a programmer could love. I had no intention of falling into that trap!
Of course, nothing ever works out exactly as planned. FogBUGZ was popular. Really popular. It accounts for a significant chunk of Fog Creek's revenue and sales are growing steadily. The People won't stop buying it.
So we did version 2.0. This was an attempt to add some of the most obviously needed features. While David worked on version 2.0 we honestly didn't think it was worth that much effort, so he tended to do things in what you might call an "expedient" fashion rather than, say, an "elegant" fashion. Certain, ahem, design issues in the original code were allowed to fester. There were two complete sets of nearly identical code for drawing the main bug-editing page. SQL statements were scattered throughout the HTML hither and yon, to and fro, pho and ton. Our HTML was creaky and designed for those ancient browsers that were so buggy they could crash loading about:blank.
Yeah, it worked brilliantly, we've been at zero known bugs for a while now. But inside, the code was, to use the technical term, a "big mess." Adding new features was a hemorrhoid. To add one field to the central bug table would probably require 50 modifications, and you'd still be finding places you forgot to modify long after you bought your first family carplane for those weekend trips to your beach house on Mars.
A lesser company, perhaps one run by an executive from the express-package-delivery business, might have decided to scrap the code and start over.
Did I mention that I don't believe in starting from scratch? I guess I talk about that a lot.
Anyway, instead of starting from scratch, I decided it was worth three weeks of my life to completely scrub the code. Rub a dub dub. In the spirit of refactoring, I set out a few rules for this exercise.
I went through each source file, one at a time, top to bottom, looking at code, thinking about how it could be better structured, and making simple changes. Here are some of the kinds of things I did during these three weeks:
Over three weeks the code got better and better internally. To the end user, not too much changed. Some fonts are a little nicer thanks to CSS. I could have stopped at any point, because at any given time I had 100% working code (and I uploaded every checkin to our live internal FogBUGZ server to make sure). And in fact I never really had to think very hard, and I never had to design a thing, because all I was doing was simple, logical transformations. Occassionally I would encounter a weird nugget in the code. These nuggets were usually bug fixes that had been implemented over the years. Luckily I could keep the bug fix intact. In many of these cases, I realized that had I started from scratch, I would have made the same bug all over again, and may not have noticed it for months or years.
I'm basically done now. It took, as planned, three weeks. Almost every line of code is different now. Yep, I looked at every line of code, and changed most of them. The structure is completely different. All the bug-tracking functionality is completely separate from the HTML UI functionality.
Here are all the good things about my code scrubbing activity:
Much of the literature on refactoring is attributable to Martin Fowler, although of course the principles of code cleanups have been well known to programmers for years. An interesting new area is refactoring tools, which is just a fancy word for programs that do some of this stuff automatically. We're a long way from having all the good tools we need -- in most programming environments you can't even do a simple transformation like changing the name of a variable (and having all the references to it change automatically). But it's getting better, and if you want to start one of those scrawny companies hawking programming tool geegaws, or make a useful contribution to open source, the field is wide open.
You’re reading Joel on Software, stuffed with years and years of completely raving mad articles about software development, managing software teams, designing user interfaces, running successful software companies, and rubber duckies.
I’m Joel Spolsky, co-founder of Fog Creek Software, a New York company that proves that you can treat programmers well and still be highly profitable. Programmers get private offices, free lunch, and work 40 hours a week. Customers only pay for software if they’re delighted. We make Trello, insanely simple project management, FogBugz, an enlightened bug tracker designed to help great teams develop brilliant software, and Kiln, which simplifies source control. I’m also the co-founder and CEO of Stack Exchange. More about me.