The Debugging Golden Rule

Main Thread May 19, 2014 • 2 min read

Don't question others until you've questioned yourself.

Developers, especially new developers, often forget this when debugging. We jump into the debugger. We add tracing statements. We review the commit log.

Such actions can be misguided. Before debugging the code we must follow a moral code. Debugging needs a Golden Rule. A rule to remind developers of a few important facts of debugging.

99% of the time it's you

I had an excellent TA for my introductory Computer Science course. He gave great advice for improving your craft. Some of which became the foundations for routines of a good developer.

In one of our more difficult labs he expressed his frustration with the class:

Listen up! Stop asking me, "What's wrong with gcc?" gcc has been widely used for over three decades. You have been programming for half a semester. gcc is not broken!

I remember his words anytime I start questioning others. A far majority of the time, the bug is in my code.

Avoid tunnel vision

Debugging is the art of asking the right questions. If you start by questioning others, you will likely waste your time asking the wrong questions.

We've all done it. A recent upgrade revealed a bug in the code. Now you have a bug in your brain: it's the upgrade.

Of course you should question the upgrade. But question question other changes too.

You still have to fix it

Let’s say you prove the language has a bug, Internet Explorer behaves differently, or the developer before you broke the build. What then?

Well, you still have to fix it. Even when it is not you, you still must develop the fix. No point in focusing on blame.

Following the Debugging Golden Rule keeps developers grounded, focused, and part of the solution. Remember it the next time you find a bug in the code.

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