Word of the Week: 16 Nov 2020

:feature:

n. 1. A good property or behavior (as of a program). Whether it was intended or not is immaterial.

2. An intended property or behavior (as of a program). Whether it is good or not is immaterial (but if bad, it is also a {misfeature}).

3. A surprising property or behavior; in particular, one that is purposely inconsistent because it works better that way — such an inconsistency is therefore a {feature} and not a {bug}. This kind of feature is sometimes called a {miswart}; see that entry for a classic example.

4. A property or behavior that is gratuitous or unnecessary, though perhaps also impressive or cute. For example, one feature of Common LISP’s `format’ function is the ability to print numbers in two different Roman-numeral formats (see {bells, whistles, and gongs}).

5. A property or behavior that was put in to help someone else but that happens to be in your way.

6. A bug that has been documented. To call something a feature sometimes means the author of the program did not consider the particular case, and that the program responded in a way that was unexpected but not strictly incorrect. A standard joke is that a bug can be turned into a {feature} simply by documenting it (then theoretically no one can complain about it because it’s in the manual), or even by simply declaring it to be good. “That’s not a bug, that’s a feature!” is a common catchphrase. See also {feetch feetch}, {creeping featurism}, {wart}, {green lightning}.

The relationship among bugs, features, misfeatures, warts, and miswarts might be clarified by the following hypothetical exchange between two hackers on an airliner:

A: “This seat doesn’t recline.”

B: “That’s not a bug, that’s a feature. There is an emergency exit door built around the window behind you, and the route has to be kept clear.”

A: “Oh. Then it’s a misfeature; they should have increased the spacing between rows here.”

B: “Yes. But if they’d increased spacing in only one section it would have been a wart — they would’ve had to make nonstandard-length ceiling panels to fit over the displaced seats.”

A: “A miswart, actually. If they increased spacing throughout they’d lose several rows and a chunk out of the profit margin. So unequal spacing would actually be the Right Thing.”

B: “Indeed.”

`Undocumented feature’ is a common, allegedly humorous euphemism for a {bug}.

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