Wednesday, 15 June 2011

Coe's Second Law Of Software Development

Before I begin, let me just put it out there that I really like the Zend Framework. I know, I know, laying down your cards about your favourite editor/framework/OS/whatever is liable to set off holy wars, but I really like ZF. It’s clean, and I like the mix-and-match properties of it that allow me to use only as much of the framework as I need. It’s this very property that I’ve used to great advantage in Project Alchemy and Portico. But I’ve always had one complaint about it.

The documentation in the reference guide, and to a roughly equal extent, in the PHPDoc navigator, is really flaky. The full functionality isn’t properly described in the reference guide, and the PHPDoc doesn’t provide enough information about the API. I’ve found, on several occasions, that I have to dig into the code simply in order to figure out how to use some methods.

Anthony Wlodarski, of, sees this as a positive of Zend Framework; that when ZF community wonks tell you to RTFS, it really is for your own good; that ZF really is that self-documenting. He says,

One thing I learned early on with ZF was that the curators and associates in the ZF ecosystem always fall back to the root of “read the code/api/documentation”. With good reason too! It is not the volunteers simply shrugging you off but it is for your own good

Unfortunately, it’s been my experience that self-documenting code isn’t. Let’s call that “Coe’s Second Law Of Software Development” (the First being when it happens, you’ll know). This is how strongly I feel about the issue. Far and away, the code itself is always the last place you want to look to figure out how it works, and only ever if you have a fair amount of time on your hands, because deciphering another developer’s idiosyncrasies is harder than writing new code. And if you have to look through that code to figure out what the correct usage of the tool is, then someone isn’t doing their job properly, particularly when Zend Framework has the backing of Zend.

I’ve been working for $EMPLOYER$ for more than a year now, and I’ve worked with a number of our internal tools, and across the board, I keep getting bit by the fact that our self-documenting code isn’t. Self-documenting code means that there’s no easily-accessible, central repository of information about how the tools are supposed to work, or about what inputs to provide and outputs to expect. Self-documenting code means that when something goes wrong, and the person who originally wrote the code, the poor sap who has to correct the problem now has to figure out what the code is supposed to do. Self-documenting code means that when your prototypes (or even production tools!) fail without a clear error code, you have to either start shotgun debugging, trying to figure out what you’re doing wrong (or what changed); or you have to ask the project manager, who will ask a developer to dig through the code. This increases the turnaround time on all problems.

Self-documenting code is fine when you’re writing little noddy programs for first-, second-, and even some third-year classes, where the functionality is defined in the assignment description, and the problems straightforward enough that what you’re doing is actually clear at a quick glance. When you’re writing tools for distribution to parties outside of the small group of people who are developing it, you owe it to yourself, to your QA team, to your present and future colleagues, and more importantly to your users, to write good, clear documentation, and to do so ahead of time, because then you only have to update the documentation to reflect what changed about your plan.

But remember, when someone tells you excitedly that their code is self-documenting, remember: self-documenting code isn’t.

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