Metasyntactic variable

A metasyntaktische variable is a variable in computer program code, which is used exclusively for the appointment of any entities in examples. A metasyntaktische variable has no other significance.

The term comes from the programming, where it is used most. A programmer uses a metasyntaktische variable is usually not in a real, finished program if he can instead use a meaningful name.

The name of the term comes from the fact that the variables are used at a higher level of language than the program, namely the description ( meta-language ).

They often occur in series and are culture- specific, such as

• Foo, bar, foobar, baz qux, quux, ... ( with variations) is very common in example source code
• Needle and haystack (English needle and haystack; see metaphor ) in functions for searching strings.
• Alice, bob, eve, trudy predominantly in cryptographic issues and in communicating (see Alice and Bob)
• Bla, blub, blah in German-speaking ( sounds which are normally for content verbiage )
• Spam and eggs specifically in Python
• Fnord

Foo Mainly occurs as an exemplary object in many example programs.

There are also " metasyntaktische values ​​," the number 42 as the answer to life, the universe and all the rest, as alleged and the illuminates as checksum latter also the fifth in the German-speaking countries as well as the 4711 and the 08 23 / 15 very common. Finally, for 32 -bit values ​​or hexadecimal numbers as DEADBEEF in use (see Hexspeak ). As metasyntaktische values ​​for domain name "example.com ", " example.net " and " example.org " were defined.

In humorous RFC 3092 a statement on the etymology of Foo was submitted and the order of variables on metasyntaktischen bar, baz, qux, quux corge, grault, garply, waldo, fred, Plugh xyzzy, thud fixed.