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In [[computer programming]] a '''naming convention''' is a set of rules for choosing the character sequence to be used for an [[identifier]]s.
Reasons for using a naming convention (as opposed to allowing people, eg, [[programmer]]s, to choose any character sequence) include the following:
Naming conventions are commonly used for various purposes:
* to embedprovide useful information aboutto thea entityreader, sucheg, asan itsidentifier's type and intended use, in the identifier (Seesee: [[Hungarian notation]]); or its intended use
* to ensureenhance clarity (for example by disallowing overly long names or abbreviations); ▼* to work around restrictions imposed by the language on what an identifier may look like (See: [[CamelCase|CamelCase notation]]);
▲* to ensure clarity (for example by disallowing overly long names or abbreviations);
Programmers tend to be very picky about naming conventions, andThe choice of naming conventions can becomebe an enormously controversial issue, with partisans of each holding theirs to be the best and others to be inferior.
== Multiple-word identifiers ==
As most programming languages do not allow spaces in identifiers, some system must be devised when a programmer wishes to use a name containing multiple words. There are several in widespread use; each has a significant following, though sometimes one dominates amongst users of a particular [[programming language]]. There are also some programmers who eschew multiple-word names entirely, and so use none of these systems (see the section below on the amount of information in identifiers).
A common recommendation is "Use meaningful identifiers." A single [[word]] may not be sufficiently meaningful, or specific, as multiple words.
One approach is to replace spaces with another character. The two characters commonly used for this purpose are the hyphen ('-') and the underscore ('_'), so the two-word name ''two words'' would be represented as ''two-words'' or ''two_words''. The hyphen is arguably the easier to type and more readable of these, and is used by nearly all programmers of [[Lisp programming language|Lisp]], [[Scheme programming language|Scheme]], and other languages that permit hyphens in identifiers. However, many other languages reserve the hyphen for use as the [[subtraction]] operator, and so do not permit it in identifiers. Thus some programmers of these languages use underscores instead. However, underscores are somewhat harder to type due to their ___location on most [[English language]] [[keyboard]]s, and so this solution has not been universally adopted; it is, however, in fairly widespread use among programmers of [[C programming language|C]], [[Perl]], and many [[scripting language]]s. ▼As most [[programming language]]s do not allow the [[whitespace_(computer science)|whitespace]] in identifiers, a method of delimiting each word is needed (to make it easier for subsequent readers to interpret the character sequence). There are several in widespread use; each has a significant following.
▲One approach is to replacedelimit spacesseparate words with anothera [[alphanumeric|nonalphanumeric]] character. The two characters commonly used for this purpose are the hyphen ('-') and the underscore ('_'), so the two-word name ''two words'' would be represented as ''two-words'' or ''two_words''. The hyphen is arguably the easier to type and more readable of these, and is used by nearly all programmers of [[Lisp programming language|Lisp]], [[Scheme programming language|Scheme]], and other languages that permit hyphens in identifiers. However, many other languages reserve the hyphen for use as the [[subtraction]] operator, and so do not permit it in identifiers. Thus some programmers of these languages use underscores instead. However, underscores are somewhat harder to type due to their ___location on most [[English language]] [[keyboard]]s, and so thisThis solution has not been universally adopted; it is , however, in fairly widespread use among programmers of [[C programming language|C]], [[Perl]], and many [[scripting language]]s.
An alternate approach, developed mostly as an alternative to the underscore in languages that do not permit hyphens, is to omit the space and indicate word boundaries using capitalization, thus rendering ''two words'' as either ''twoWords'' or ''TwoWords''. This is called [[CamelCase]], among other names. ▼
▲An alternate approach, developed mostly as an alternativeapproachis to the underscore in languages that do not permit hyphens, is to omit the space and indicate word boundaries using capitalization, thus rendering ''two words'' as either ''twoWords'' or ''TwoWords''. This is called [[CamelCase]], among other names.
== Information in identifiers ==
There is significant disagreement over whether it is permissible to use short (ie, containing few characters) identifiers. The argument being that it is not possible to encode much information, if any, in a short sequence of characters. Whether programmers prefer short identifiers because they are too lazy to type, or think up, longer identifiers, or because in many situations a longer identifier simply clutters the visible code and provides no worthwhile additional benefit (over a shorter identifier) is an open research issue.
There is significant disagreement over how much information to put in identifiers. This was driven initially by technical reasons, as some early programming languages only allowed identifiers of a certain length. Thus in the standard C library (C was initially one of those languages), one finds ''atoi'' as the name of a function that converts [[ASCII]] strings to [[integer]]s. In Lisp, one would be more likely to encounter the same function named as ''ascii-to-integer'' or similar. However, the use of shorter identifiers has outlived those technical restrictions, partly as heritage (it continues more commonly in those languages that once had the restrictions), and partly out of ease of use -- it's simply easier to type shorter identifiers, especially when the identifier is used frequently. Those who prefer the longer identifiers argue that the difficulty of typing the longer identifiers is outweighed by the ease of reading code that is more descriptive rather than peppered with impenetrable acronyms and abbreviations.
InThere additionare toseveral thewell issue of length of identifiers in their descriptive capacity, there are also severalknown systems for codifying specific technical aspects of a particular identifier in the name. Perhaps the most well-known is [[Hungarian notation]], which encodes the [[datatype|type]] of a variable in its name. Several more minor conventions are widespread; one example is the convention of namingexcluding variablesthe inuse C andof [[ C++lowercase]] withletters anin initialidentifiers lowercaserepresenting letter,macros andin namingC user-definedand datatypes with an initial capital letter[[C++]]. ▼
==External links==
*[http://www.coding-guidelines.com/cbook/sent787.pdf A detailed analysis of identifier naming issues]
▲In addition to the issue of length of identifiers in their descriptive capacity, there are also several systems for codifying specific technical aspects of a particular identifier in the name. Perhaps the most well-known is [[Hungarian notation]], which encodes the [[datatype|type]] of a variable in its name. Several more minor conventions are widespread; one example is the convention of naming variables in C and [[C++]] with an initial lowercase letter, and naming user-defined datatypes with an initial capital letter.
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