![]() Within class declarations and definitions as well, a prefix of - is used to indicate member methods and variables, while prefix + indicates class elements. ![]() The prefix is also used on the keywords interface, implementation, and end to express the structure of class definitions. In Objective-C, string literals preceded with " are instances of the object type NSString or, since clang v3.1 / LLVM v4.0, NSNumber, NSArray or NSDictionary. 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". The last global variable subtree may be referenced indirectly by a caret and the last subscript this is referred to as a "naked reference". ![]() Routines (used for procedures, subroutines, functions) and global variables (database storage) are prefixed by a caret (^). " $Z" precedes non-standard intrinsic function names. In the MUMPS programming language, " $" precedes intrinsic function names and "special variable names" (built-in variables for accessing the execution state). Binary variables are prefixed by an " &". ![]() In mIRC script, identifiers have a " $" sigil, while all variables have a " %" prefixed (regardless of local or global variables or data type). In MAPPER (aka BIS), named variables are prefixed with "" because strings or character values do not require quotes. The later CLC-Intercal added " ("whirlpool") for a variable that can contain no value (used for classes) and " _" used to store a modified compiler. " (called "spot") for 16-bit values, " :" (called "twospot") for 32-bit values, " ," ("tail") for arrays of 16-bit values and " " ("hybrid") for arrays of 32-bit values. In the esoteric INTERCAL, variables are a 16-bit integer identifier prefixed with either ". Programmers can also create their own sigils. Other sigils include ~s for strings and ~D for dates. For example, ~r(foo) is a regular expression of "foo". In Elixir, sigils are provided via the " ~" symbol, followed by a letter to denote the type of sigil, and then delimiters. Similarly, constant names are prefixed with " #$" (pronounced "hash-dollar"). In CycL, variables are prefixed with a " ?" sigil. Similarly, some programmers surround constants with +. While this is only convention, and not enforced, the language itself adopts the practice (e.g., *standard-output*). In Common Lisp, special variables (with dynamic scope) are typically surrounded with * in what is called the " earmuff convention". In CLIPS, scalar variables are prefixed with a " ?" sigil, while multifield (e.g., a 1-level list) variables are prefixed with " $?". ", used with object attribute accessors (i.e., instance variables). Prominent examples of twigils in Raku include " ^" ( caret), used with self-declared formal parameters ("placeholder variables"), and ". ![]() Raku also uses secondary sigils, or twigils, to indicate the scope of variables. In Perl, the sigils do not specify fine-grained data types like strings and integers, but the more general categories of scalars (using a prefixed " $"), arrays (using " hashes (using " %"), and subroutines (using " &"). Larry Wall adopted shell scripting's use of sigils for his Perl programming language. Many BASIC dialects use other sigils (like " %") to denote integers and floating-point numbers and their precision, and sometimes other types as well. Consequently, programmers outside America tend to pronounce $ as "string" instead of "dollar". The best known example of a sigil in BASIC is the dollar sign (" $") appended to the names of all strings. The use of sigils was popularized by the BASIC programming language. Sigils can be used to separate and demarcate namespaces that possess different properties or behaviors. Sigil, from the Latin sigillum, meaning a "little sign", means a sign or image supposedly having magical power. In computer programming, a sigil ( / ˈ s ɪ dʒ əl/) is a symbol affixed to a variable name, showing the variable's datatype or scope, usually a prefix, as in $foo, where $ is the sigil. ![]()
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