feature
1. A good property or behaviour (as of a program).
Whether it was intended or not is immaterial.
2. An intended property or behaviour (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 behaviour; 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}.
4. A property or behaviour 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 behaviour 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 catch-phrase. Apparently there is a
Volkswagen Beetle in San Francisco whose license plate reads
"FEATURE".
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 euphemism for a {bug}.
7. An attribute or function of a {class} in {Eiffel}.
[{Jargon File}]
(1995-10-22)