CamelCase |
CamelCase is a common name for the practice of writing compound noun and adjectives or phrases where the words are joined without whitespaces, and each word is capitalization within the compound. This practice is known by a large variety of names, including BiCapitalization, InterCaps, MixedCase, etc, and many of its users do not ascribe a name to it at all. Editors of the Oxford English Dictionary describe words using this format as having medial capitals.
CamelCase is a standard identifier naming convention for several programming languages, and has become fashionable in marketing for names of products and companies. Outside these contexts, however, CamelCase is rarely used in Formal written English - regional differences, and most style guides recommend against it.
=Variations and synonyms=
The CamelCase name comes from the uppercase bumps in the middle of the compound word, suggesting the humps of a camel. It is not related to the Camel book ( Programming Perl ), which uses all-lowercase identifiers with underscores in its sample code.
camelCaseLooksLikeThis lowerCamelCaseLooksTheSame UpperCamelCaseLooksLikeThis
There are two common varieties of CamelCase, distinguished by their handling of the initial letter. The variety in which the first letter is capitalized is commonly called UpperCamelCase , Pascal programming languageCase , or BiCapitalized . The variety in which the first letter is left as lowercase is commonly called lowerCamelCase or sometimes simply camelCase . For clarity, this article will use the terms UpperCamelCase and lowerCamelCase , respectively.
The term StudlyCaps is similar — but not necessarily identical — to CamelCase. It is sometimes used in reference to CamelCase but can also refer to random mixed capitalization (as in MiXeD CaPitALiZaTioN ) as popularly used in online culture.
Other synonyms include:
=Coding standards=
Internal capitalization is recommended or enforced by many computer systems, and mandated by the coding standards of many programming languages — such as Mesa programming language, the systems programming language of the Xerox Alto (late 1970s), or the modern language Java programming language. It is also the official convention for file names in Java and of the Amiga personal computers.
Coding standards often distinguish between UpperCamelCase and lowerCamelCase, typically specifying which variety should be used for specific kinds of entities: variable (computer science)s, field (computer science), method (computer science)s, procedure (computer science), type (computer science), etc..
For instance, the Java coding style dictates that UpperCamelCase should be used for class (computer science), and lowerCamelCase should be used for instance (computer science) and member (computer science). The original Hungarian notation for programming specifies that a lowercase abbreviation for the usage type (not data type) should be prefixed on all variable names, with the remainder of the name in UpperCamelCase; as such it is a form of lowerCamelCase.
ISO-11179 and the NIEM standards require that XML Data Elements use UpperCamelCase and XML Attributes use lowerCamelCase.
Some Wikis use CamelCase as the manner of distinguishing which words are to be considered links and which are not, with the CamelCase words being automatically linked. This was the style used by the earliest wikis, and some of their users regard this as the standard manner of doing wiki links, though many modern wikis (such as those using the MediaWiki software, such as Wikipedia) do not use this system, instead allowing free links to any word or phrase that is specifically delimited by the author.
=History=
CamelCase has been sporadically used since ancient times, for example as a traditional spelling style for surnames in certain ethnicities, such as the Scotland McLean or the the Netherlands-American deJong or DeJong . In the early 20th century, it was used occasionally for trademarking corporations and products, such as the CinemaScope film projection system introduced in the 1950s.
However, the use of CamelCase became widespread only in the 1970s or 1980s, when it was adopted as a standard or alternative identifier naming convention for multi-word identifiers in several programming languages. There are various possible origins, and it may have developed independently from multiple sources.
= Background for modern usage =
In programs of any significant size, there is a need for descriptive (hence multi-word) identifiers, like previous balance or end of file . Writing the words together as in endoffile is not satisfactory because the names often become unreadable. Therefore, the pioneer programming language COBOL allowed a hyphen ( - ) to be used between words of compound identifiers, as in END-OF-FILE . The contemporary algebraic language Fortran reserved the hyphen as the minus operator, but allowed spaces to be arbitrarily embedded into identifiers, so that TOTAMP could be written TOT AMP (or TO TAMP ). However, this feature was of little use because most Fortran compilers did not allow identifiers longer than six letters.
The common punched card character sets of the time had no lower-case letters and no special character that would be adequate as a word separator in identifiers. However, by the late 1960s the ASCII character set standard had been established, allowing the designers of the C language to adopt the underscore character _ as a word joiner. Underscore-separated compounds like end_of_file are still prevalent in C programs and libraries.
==The Lazy Programmer origin==
One explanation of the origins of CamelCase in Computing claims that the style originated within the culture of C programming language and hacker culture, who found it more convenient than the standard underscore-based style.
On most keyboards, the underscore key is inconveniently placed. Additionally, in some fonts the underscore character can be confused with a minus sign; it can be overlooked because it falls below the string of characters, or it can be lost entirely when displayed or printed underlined, or when printed on a dot-matrix printer with a defective pin or misaligned ribbon. Moreover, compiler limits on identifier length and the small computer displays available in the 1970s worked together to encourage brevity. So many programmers chose to use CamelCase instead, because it yielded legible compound names with fewer keystrokes and fewer characters.
==The Alto Keyboard origin==
Another explanation is that CamelCase started at Xerox PARC around 1978, with the Mesa programming language developed for the Xerox Alto computer. This machine lacked an underscore key, and the hyphen and space characters were not permitted in identifiers, leaving CamelCase as the only viable scheme for readable multiword names. The PARC Mesa Language Manual (1979) included a coding standard with specific rules for Upper- and lowerCamelCase which was strictly followed by the Mesa libraries and the Alto operating system.
The Smalltalk language, which was developed originally on the Alto and became quite popular in the early 1980s, may have been instrumental in spreading the style outside PARC. CamelCase was also used in the PostScript graphics language, another very popular PARC invention. Further boost was provided by Niklaus Wirth — the inventor of Pascal programming language — who acquired a taste for CamelCase during a sabbatical at PARC, and used it in Modula, his next programming language.
==History of the CamelCase name==
The style had no definite name initially. The earliest known occurrence of InterCaps on Usenet is in an April 1990 post to the group alt.folklore.computers by . [http://groups.google.com/groupsselm=newton.212.30563F09%40michelob.wustl.edu&output=gplain].
==Mainstream usage==
During the same period in which personal computers exposed hacker culture to a more mainstream audience in the 1980s and 1990s, CamelCase became fashionable for corporate trade names, first in computer-related fields but later expanding further into the mainstream. Here are some examples ranging from the 1960s to the 2000s: *ShopKo Stores, Inc. (1962) *AstroTurf (1967) *CompuServe (1969) *ConAgra Foods, Inc. (1971) (formerly Consolidated Mills) *MicroSoft (now Microsoft) (1975) *VisiCalc (1979) *EchoStar Communications Corporation (1980) *WordPerfect (1982) *HeLa / HeLa cell (1983) *Novell NetWare (1983) *BellSouth (1984) *MacWorks (1984) *Adobe PageMaker (1985) *ClarisWorks (1987) *HarperCollins Publishers (1990) *QuickTime (1991) *ThinkPad (1992) *Oulipo (1993) *EarthLink (1994) *PlayStation (1994) *WorldCom (now MCI) (1995) *RadioShack (formerly Radio Shack) (1996) *AppleWorks (1997) *VisiBroker (1997) *DaimlerChrysler (1998) *PricewaterhouseCoopers (1998) *StarCraft (1998) *UnitedHealth Group (formerly United HealthCare) (1998) *BlackBerry (1999) *CloneCD (1999) *ExxonMobil (1999) *SpongeBob SquarePants (1999) *FedEx Corporation (formerly Federal Express) (2000) *GlaxoSmithKline (2000) *OpenOffice.org (2000) *AmerisourceBergen Corporation (2001) *ChevronTexaco (now Chevron Corporation) (2001) *ConocoPhillips (2002) *SuperAmerica (date unknown)
This fashion has become so pervasive that it is often incorrectly applied to names that do not use it officially, as in Transamerica (Transamerica), Mozilla Firefox (Firefox), Usenet (Usenet) , Time Warner (Time Warner, whose new logo does appear in CamelCase fashion), Game Boy (Game Boy), and KarmelKorn (Karmelkorn).
=See also=
*All caps *CamelCase and Wiki *StudlyCaps
=References=
*[http://www.netbros.com/CamelCase NetVillage: What is CamelCase ]
=External links=
*[http://c2.com/cgi/wikiCamelCase Examples and history of CamelCase] *[http://msdn.microsoft.com/library/default.aspurl=/library/en-us/cpgenref/html/cpconcapitalizationstyles.asp .NET Framework General Reference Capitalization Styles] *[http://www.theslot.com/webnames.html What s in a nAME(cq)], by Bill Walsh, at The Slot *[http://www.microsoft.com/typography/ctfonts/WordRecognition.aspx The Science of Word Recognition], by Kevin Larson, Advanced Reading Technology, Microsoft Corporation|
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