metasyntactic variables

from wikipedia, the free encyclopedia.

a metasyntactic variable can either be a placeholder name, a kind of alias term, commonly used to denote the subject matter under discussion, or a random member of a class of things under discussion.

the term originates from computer programming and other technical contexts, and is commonly used in examples by hackers and programmers.

the use of a metasyntactic variable is helpful in freeing a programmer from creating a logically named variable, although the invented term may also become sufficiently popular and enter the language as a neologism. the word foo is the canonical example.

the phenomenon is similar to the use in algebra of x, y and z for unknown variables, and a, b and c for unknown constants. “widgets” are also used in business to indicate an as-yet-unspecified product and are frequently sold by the acme company.

metasyntactic variables are so called because:

they are variables in the metalanguage used to talk about programs, etc.
see also pseudocode
they are variables whose values are often variables as in usages like
the value of ƒ ( foo, bar ) is the sum of foo and bar

examples

→ nonsense words	→ english words	→ numbers
→ names of people	→ military names	→ other names
→ place names	→ other languages

nonsense words

foo, bar and baz

foo is the first metasyntactic variable, commonly used to represent an as-yet-unspecified term, value, process, function, destination or event but seldom a person (see ned baker).

it is sometimes combined with bar to make foobar. this suggests that foo may have originated with the world war ii slang term fubar, as an acronym for fucked/fouled up beyond all recognition/repair, although the wikipedia jargon file makes a reasonably good case that foo predates fubar.

foo was also used as a nonsense word in the surrealistic comic strip smokey stover that was popular in the 1940s and 1950s.

another usage of foo is as an abreviation of the phrase “forward observation officer” (or observer). apparently foos used to go places well forward of normal troops in battle and leave a stylised chalk graffiti of a person looking over a wall with the words “foo was here”.

the term “kung foo” has come to mean skill in computer programming. this is actually used (though misspelled) in the movie the core.

bar, the canonical second metasyntactic variable, typically follows foo.

baz, the canonical third metasyntactic variable, is commonly used after foo and bar.

foo, bar, and baz are often compounded together to make such words as foobar, barbaz, and foobaz.

quux

quux, introduced by guy l. steele, jr., is the canonical fourth metasyntactic variable, commonly used after baz. however, more recently qux has become more common as the fourth variable, displacing quux as the fifth. a probable reason for this is that quux is often followed by the series quuux, quuuux, quuuuux etc. and qux fits this pattern perfectly.

bat

bat is used by some programmers as an alternative to quuux.

xyzzy

the word xyzzy is the “magic word” from the colossal cave adventure, and therefore is often used as a metasyntactic variable, especially by old-school hackers.

shme

infrequently used in various environments such as berkeley, geoworks, ingres, quovadx. pronounced /shmeh/ with a short /e/.

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english words

spam and eggs

spam and eggs are the canonical metasyntactic variables used in the python programming language. this is a reference to a famous comedy sketch by monty python, after which the language is named.

needle and haystack

needle and haystack are commonly used in computer programming to describe the syntax of functions that involve a search parameter and a search target, such as searching a substring within a string; with these two words, derived from the idiom “to find a needle in a haystack”, it is clearer where the substring for which to search goes, and where the string in which to search goes. this can be seen, for instance, in the documentation for some functions in the computer language php.

other words used as metasyntactic variables include:

beekeeper
blah
blarg
bleh
corge
doip
dothestuff
garply

glarb
grault
hoge
kalaa
mum
plugh
puppu
stuff

sub
temp
test
thud
var
waldo
momo.

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numbers

23: the number 23 is also commonly used as an integer example—particularly when the connotations associated with 42 are undesirable.
42: the number 42 is often a common initializer for integer variables, and acts in the same vein as a “metasyntactic value”. it is taken from douglas adams’ the hitchhiker’s guide to the galaxy, where deep thought concluded that it was the answer to life, the universe, and everything.
47: the number 47 is sometimes used instead of 42 above, and is used mainly by members of the 47 society, or new trek fans.
69: 69 is often used as an example number. popular among hackers as an addition to metasyntactic variables (foo69, bar69), also used in all sorts of hacks. 69 is popular because of its reference to a sexual position. it is also because it is the largest number whose factorial can be calculated by a pocket calculator limited to standard scientific notation with a 2 digit exponent.
0815: 0815 (named after the repetitive and boring mg 08/15-training) is used in german as either a random number or to reflect something normal or boring.
1337: stands for leet, in leetspeak, being, thus, commonly used.
4711: 4711 is most commonly used in german computer speak as a random member of a set. it is a brand of eau de cologne, originally named after the number of the manufacturer’s house in cologne.

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names of people

j. random and ned baker

j. random and ned baker are the names of archetypal users.
j. random hacker and j. random user are also common.

alice and bob

alice and bob are names of the archetypal individuals used as examples in discussions of cryptographic protocols. others include:

carol - a participant in three- and four-party protocols
dave - a participant in four-party protocols
ellen - a participant in five- and six-party protocols
frank - a participant in six-party protocols, and so on
eve or oscar - an (evil) eavesdropper
mallory or mallet - a malicious active attacker
trent - a trusted arbitrator
walter - a warden
peggy - a prover
victor - a verifier
sam - a trusted server (uncle sam)
charlie - a challenger or opponent
trudy - an intruder or malicious entity

bob, alice and carol may have come from the 1969 movie bob & carol & ted & alice, or from the fact that they are common english names starting with a, b and c, the first letters of the alphabet.

dave, ellen, and frank are the next three letters.

some people continue this pattern, using gloria or another similar term for the seventh participant, and so on (maintaining the pattern female, male, female, male …).

fred and barney

after the characters in the cartoon series the flintstones.

the most famous use of these is the example code in learning perl.

fred is also known to have been used simply because the keys are close together on the qwerty keyboard.

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military names

some names are most commonly used in military context.

private snuffy
susie rottencrotch or jane rottencrotch: from the movie full metal jacket
gi joe or gi jane: beetle bailey from the comic strip of the same name
gomer pyle or private pyle: from the television show of the same name,
also popularized by the movie full metal jacket

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other names

sometimes placeholders from other contexts will be used:

john doe
jane roe
richard roe
a. n. other
john q. public
bloggs or joe bloggs
joe soap and tom
dick and harry.

law schools

the generic case name push v. pull is used as a variable.

law or accounting firms

sometimes referred to with names like dewey cheatham & howe
ie. do we cheat ‘em and how!

other nonsense names

come from swapping initials e.g. j. pennings.

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place names

smallville and metropolis: smallville and metropolis are fictional places from the superman series of comic books.
these are used to contrast urban and rural characteristics.
anywhere, anytown and nowhere: anywhere, usa or anytown, usa connotes genericness.
nowhere sometimes suggests that the entry is invalid.
middle of nowhere / in the sticks / east buttfuck / east boofu: unlike nowhere, these metasyntactic variables indicate extreme remoteness
and suggest contempt.
podunk university: this term is sometimes a placeholder for a generic university.
y.u. bum university: this term is sometimes a placeholder for a less generic university.
pronounced like “why you bum, you.”

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other languages

of course, other languages have their own metasyntactic variables.
some examples:

→ chinese	→ danish	→ dutch	→ italian
→ italian (suisse)	→ french	→ greek	→ japanese
→ yiddish	→ portuguese	→ finnish	→ estonian
→ german	→ romanian	→ french (belgium)	→ turkish
→ spanish	→ hebrew	→ tamil	→ hungarian
→ hindi	→ russian	→ swedish	→ notes

chinese

jia
yi
bing
ding