1. [common] A good property or behavior (as of a program). Whether it was intended or not is immaterial.
2. [common] 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. [common] 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
, 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."
`Undocumented feature' is a common, allegedly humorous euphemism for a bug
. There's a related joke that is sometimes referred to as the "one-question geek test". You say to someone "I saw a Volkswagen Beetle today with a vanity license plate that read FEATURE". If he/she laughs, he/she is a geek (see computer geek
, sense 2).