Typical Programmer

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How to develop unmaintainable software

14 Oct 2013

I get paid to take on technical debt. In my work I see a lot of hard-to-maintain code, and I see many of the same avoidable problems over and over.

I specialize in debugging, fixing, maintaining, and extending legacy software systems. My typical client has a web site or internal application that works, more or less, but the original developer isn’t available. Business requirements have changed and the software hasn’t kept up. Or my client has something that is “almost finished” but they parted ways with the developer after using up their budget and schedule. Usually there’s a list of missing features and bugs.

My typical client usually has been told by other developers that they need to throw everything away and start from scratch. Most programmers don’t like maintaining code, and they especially don’t like maintaining someone else’s code. When writing code programmers often ask the wrong questions when they talk about maintainability—see Matt DuVall’s article The myth of maintainability for a good description of how that happens.

Here are some things you can do in your own software projects to keep me in business:

Don’t use version control

I’m always surprised to find big projects written in the last few years that aren’t under source code version control. When you don’t use version control the next programmer to come along has to figure out which files are part of the current system and which are obsolete or backups. The next programmer won’t have any commit messages or change logs to get the code’s history from. I covered how not to use version control in my article Introduction to Abject-Oriented Programming.

Customize your development environment. A lot.

Don’t make it easy for the next programmer to start working on the code. Require specific versions of languages and tools, and make sure they conflict with the versions that come with the operating system. Customize your Eclipse or VisualStudio or vim environment like crazy, then write macros and scripts that only work with that setup. Don’t have a disk image or scripts to replicate your development environment, and don’t bother writing any documentation—it will be intuitive.

Create an elaborate build and deployment environment

For a web site deployment to a staging or production server should look like one of these:

svn up
git pull
hg pull

Programmers can argue about simplicity and elegance in code, and then turn around and build the most elaborate and baroque build and deployment systems. This is one of the off-the-radar things that programmers do without their client or project manager reviewing or understanding it, so it easily gets out of control. While you’re chaining together eight different tools with various scripting languages remember to leave out the documentation.

###Don’t set up testing/staging platforms Changing a production system is exciting. Don’t bother with a testing/staging server. Instead have secret logins and backdoor URLs to test new features. Mix test data with real data in your database. Since you aren’t using source control keep copies of previous versions just in case. Don’t build logging into the code. Don’t disable outgoing emails, credit card authorizations, etc. during testing.

Write everything from scratch

Don’t bother with a well-understood framework like Django, Rails, or CakePHP. You can write a better templating engine, ORM, sort or hashing algorithm. I scratch my head when I see code with comments like “faster than native dictionary method” or “replacing PHP library function because parameter order sucks.”

Add dependencies to specific versions of libraries and resources…

Throw in as much third-party code as you can. Link to as many shared libraries as you need to. I’ve seen code depend on large external libraries just to get access to one function. Modify the source code of the third-party libraries so they can’t automatically be updated to a newer version, but don’t bother forking or keeping your modified versions under source code control. I will be able to diff your version with the original and figure it out.

… But don’t protect or document those dependencies

I get more urgent calls because of updates and upgrades gone wrong than for any other reason. A seemingly innocuous WordPress upgrade, Linux package update, or new jQuery release will trigger a chain reaction of failures. Don’t make your code check for the specific version or modified copy of your external resources or third-party libraries. Don’t even add a comment to remind yourself.

Use a bunch of different programming languages and stay cutting-edge

Every day HackerNews and Reddit buzz with cool new languages. Try them out on your client’s time. Any decent programmer can learn a new language in no time, so if the next programmer who gets to work on your code is a newb that’s not your problem. The boundaries between the languages, the incompatible APIs and data formats, the different server configuration requirements are all fun challenges to overcome and post about on StackOverflow. I’ve actually seen PHP web sites with pieces of Ruby wedged in because everyone knows PHP sucks and Ruby is better. Half-baked caching, aborted Rails and Node.js projects, and especially NoSQL solutions (“It’s more scaleable!”) are my bread and butter.

Where’s the programming advice?

It won’t matter much if your code is beautifully object-oriented or shiny and functional—programmers pretty much always see spaghetti code when they have to maintain a legacy system. I am good with diff and grep and Ctags, tracing through code, refactoring, and debugging. I’ll figure out the code. The most beautiful, elegant code is still hard to work with if there’s no source control, too many dependencies and customizations, and no testing/staging facility. It’s like finding one clean and nicely-decorated room in a house straight out of “Hoarders.”

Related and possibly interesting: The joys of maintenance programming.