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.
