Editing Sigil (computer programming) (section)

==Sigil use in some languages==

In [[CLIPS]], scalar variables are prefixed with a "<code>?</code>" sigil, while multifield (e.g., a 1-level list) variables are prefixed with "<code>$?</code>".

In [[Common Lisp]], special variables (with dynamic scope) are typically surrounded with <code>*</code> in what is called the "[[earmuff convention]]". While this is only convention, and not enforced, the language itself adopts the practice (e.g., *standard-output*). Similarly, some programmers surround constants with <code>+</code>.

In [[CycL]], variables are prefixed with a "<code>?</code>" sigil.<ref>{{cite web|url=http://www.cyc.com/cycl/syntax/variables/|title=Variables – Cycorp|website=www.Cyc.com|access-date=31 December 2017}}</ref> Similarly, constant names are prefixed with "<code>#$</code>" (pronounced "hash-dollar").<ref>{{cite web|url=http://www.cyc.com/cycl/syntax/constants-0/|title=Constants – Cycorp|website=www.Cyc.com|access-date=31 December 2017}}</ref>

In [[Elixir (programming language)|Elixir]], sigils are provided via the "<code>~</code>" symbol, followed by a letter to denote the type of sigil, and then delimiters. For example, <code>~r(foo)</code> is a regular expression of "foo". Other sigils include <code>~s</code> for strings and <code>~D</code> for dates. Programmers can also create their own sigils.<ref>{{cite web | url=https://elixir-lang.org/getting-started/sigils.html | title=Getting Started: Sigils | website=Elixir | access-date=18 January 2022}}</ref>

In the [[Esoteric programming language|esoteric]] [[INTERCAL]], variables are a 16-bit integer identifier prefixed with either "<code>.</code>" (called "spot") for 16-bit values, "<code>:</code>" (called "twospot") for 32-bit values, "<code>,</code>" ("tail") for arrays of 16-bit values and "<code>;</code>" ("hybrid") for arrays of 32-bit values.<ref>{{Cite web |title=C-INTERCAL 0.29 Revamped Instruction Manual |url=http://catb.org/~esr/intercal/ick.htm#Constants-and-Variables |access-date=2022-06-30 |website=catb.org}}</ref> The later CLC-Intercal added "<code>@</code>" ("whirlpool") for a variable that can contain no value (used for [[Class (computer programming)|classes]]) and "<code>_</code>" used to store a modified [[compiler]].<ref>{{Cite web |title=CLC-INTERCAL Reference |url=https://oshaboy.github.io/clc_intercal_docs/expressions.html#variables |access-date=2022-06-30 |website=oshaboy.github.io}}</ref>

In [[MAPPER]] (aka BIS), named variables are prefixed with "<" and suffixed with ">" because strings or character values do not require quotes.

In [[mIRC script]], identifiers have a "<code>$</code>" sigil, while all variables have a "<code>%</code>" prefixed (regardless of local or global variables or data type). Binary variables are prefixed by an "<code>&amp;</code>".

In the [[MUMPS (programming language)|MUMPS]] programming language, "<code>$</code>" precedes intrinsic function names and "special variable names" (built-in variables for accessing the execution state). "<code>$Z</code>" precedes non-standard intrinsic function names. "<code>$$</code>" precedes extrinsic function names. Routines (used for procedures, subroutines, functions) and global variables (database storage) are prefixed by a caret (^). The last global variable subtree may be referenced indirectly by a caret and the last subscript; this is referred to as a "naked reference".  System-wide routines and global variables (stored in certain shared database(s)) are prefixed with ^%; these are referred to as "percent routines" and "percent globals".

In [[Objective-C]], string literals preceded with "<code>@</code>" are instances of the object type <code>NSString</code> or, since [[clang]] v3.1 / [[LLVM]] v4.0, <code>NSNumber</code>, <code>NSArray</code> or <code>NSDictionary</code>. The prefix <code>@</code> is also used on the keywords <code>interface</code>, <code>implementation</code>, and <code>end</code> to express the structure of class definitions. Within class declarations and definitions as well, a prefix of <code>-</code> is used to indicate member methods and variables, while prefix <code>+</code> indicates class elements.

In the [[PHP]] language, which was largely inspired by Perl, "<code>$</code>" precedes any [[variable (programming)|variable]] name. Names not prefixed by this are considered [[constant (computer science)|constants]], [[function (computer science)|functions]] or [[Class (computer programming)|class]] names (or interface or trait names, which share the same namespace as classes).

[[PILOT]] uses "<code>$</code>" for buffers (string variables), "<code>#</code>" for integer variables, and "<code>*</code>" for program labels.

[[Python (programming language)|Python]] uses a "<code>__</code>" prefix, called ''dunder'', for [[name mangling#Python|"private" attributes]].

In [[Ruby programming language|Ruby]], ordinary variables lack sigils, but "<code>$</code>" is prefixed to [[global variable]]s, "<code>@</code>" is prefixed to [[instance variable]]s, and "<code>@@</code>" is prefixed to [[class variable]]s. Ruby also allows (strictly conventional) suffix sigils: "<code>?</code>" indicates a predicate method returning a [[Boolean function|boolean]] or a [[truth value#Computing|truthy or falsy]] value, and "<code>!</code>" indicates that the method may have a potentially unexpected effect and needs to be handled with care.<ref>{{cite web|last=Black|first=David A.|title=Bang methods; or, Danger, Will Rubyist!|date=15 August 2007|url=http://dablog.rubypal.com/2007/8/15/bang-methods-or-danger-will-rubyist|archive-url=https://web.archive.org/web/20160522235741/http://dablog.rubypal.com/2007/8/15/bang-methods-or-danger-will-rubyist|archive-date=22 May 2016}}</ref>

In [[Scheme (programming language)|Scheme]], by convention, the names of procedures that always return a boolean value usually end in "<code>?</code>". Likewise, the names of procedures that store values into parts of previously allocated Scheme objects (such as pairs, vectors, or strings) usually end in "<code>!</code>".

[[Standard ML]] uses the prefix sigil "<code>'</code>" on a variable that refers to a type. If the sigil is doubled, it refers to a type for which equality is defined. The "<code>'</code>" character may also appear within or at the end of a variable, in which case it has no special meaning.

In [[Transact-SQL]], "<code>@</code>" precedes a local variable or parameter name. System functions (previously known as global variables) are distinguished by a "<code>@@</code>" prefix. The scope of temporary tables is indicated by the prefix "<code>#</code>" designating local and "<code>##</code>" designating global.

In [[Windows PowerShell]], which was partly inspired by [[Unix shell]]s and Perl, variable names are prefixed by the "<code>$</code>" sigil.

In [[XSLT]], variables and parameters have a leading "<code>$</code>" sigil on use, although when defined in <code>&lt;xsl:param&gt;</code> or <code>&lt;xsl:variable&gt;</code> with the "<code>name</code>" attribute, the sigil is not included. Related to XSLT, [[XQuery]] uses the "<code>$</code>" sigil form both in definition and in use.

In [[Maya Embedded Language|MEL]], variable names are prefixed by "<code>$</code>" to distinguish them from functions, commands, and other identifiers.