Structure and Interpretation of Computer Programmers

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Wednesday, October 15, 2008

It was asked for: the “features” post

Someone anonymous once said:
I’m intrigued by your feature comment. Please publish said blog post!
Where said comment was:
The fact that I have stopped using the word ‘feature’ in many contexts is an entire blog post and a few therapy sessions in itself.
So here, for your delectation, is that entire blog post.

When you’re trying to decide what software people want, and indeed how to tell them that they want whatever software they’re going to get instead, that’s marketing (mainly – it’s partly sales, and there’s yet another tangential post on why I occasionally deliberately conflate marketing and sales). Marketing works in terms of features, which for the purposes of marketing means “properties or qualities of the software which we think might make people interested in that software”.

When you’re trying to decide what software to build, or trying to build the software, more specific terms are used. Initially people split requirements into two distinct groups, functional (what the system is capable of) and non-functional (how the system goes about its capabilities), but a more precise organisation is often needed. For instance, a requirement of system security might result in both functional and non-functional aspects of the system being specified.

Of course, some or all of the capabilities are also features, in fact it’s generally true that the set of all features, the set of all known requirements and the set of things the customer wants are intersecting subsets of the set of all possible qualities of a software system. Companies without an intersection between any two of these sets tend to go out of business very quickly. But the sets rarely perfectly overlap.

For instance, it’s a feature of Windows 7 that it’s named differently from Windows Vista, because Microsoft’s marketing requires that customers believe that they’ve put Vista behind them. However, it’s also a feature of Windows 7 that it not be very distinct from Vista, because marketing require that application compatibility doesn’t get broken. Hence we have the interesting situation that Windows 7 is also Windows 6.1. And if Microsoft think they’re being innovative in that version numbering policy, they should try looking up the history of SunOS/Solaris version numbers. BTW, indeed I haven’t switched my SUNW tag to JAVA, because I already use the java tag to mean the Java language and the Java platform. Marketing people can be funny sometimes.

Another example, less confusing though more contradictory, is Apple’s Snow Leopard collateral. The fact that marketing are telling us there are no new features in Snow Leopard means that “no features” is something they believe we might want to buy, which in turn makes it a featureā€¦Ā confused?

So anyway, I try to avoid using the word “feature” when I’m talking about software, because I’m usually instead talking about a capability or property of a software system, and not about marketing that software system. For instance, in Properties about a year on I described properties as a capability of the Objective-C 2.0 language, which indeed they are. It happens that properties is also a feature of the language (don’t believe that programming languages have marketing departments? What else do Apple’s tech evangelists do, if it isn’t marketing?), but in the case of that post I was talking about what can be done with properties, how properties can be used, and not how they can switch developers to Leopard from Tiger or .NET.

And in other news, it seems that badly-parked tech company founder Mercs are back in fashion.

posted by Graham Lee at 20:27  

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