Fully qualified name
Encyclopedia
In computer programming
, a fully qualified name is an unambiguous name that specifies which object
, function, or variable
a call refers to without regard to the context of the call. In a hierarchical structure
, a name is fully qualified when it "is complete in the sense that it includes (a) all names in the hierarchic sequence above the given element and (b) the name of the given element itself." Thus fully qualified names explicitly refer to namespace
s that would otherwise be implicit because of the scope
of the call. While always done to eliminate ambiguity
, this can mean different things dependent on context.
Commonly encountered applications of the notion have been given their own names, such as the fully qualified domain name and the fully qualified file name
.
, Tcl
, and Perl
use two colons (::), and Java
uses dots (.), as does Visual Basic .NET. and C#. In Java, ActionScript
, and other object-oriented languages the use of the dot is known as "dot syntax". Other examples include:
Computer programming
Computer programming is the process of designing, writing, testing, debugging, and maintaining the source code of computer programs. This source code is written in one or more programming languages. The purpose of programming is to create a program that performs specific operations or exhibits a...
, a fully qualified name is an unambiguous name that specifies which object
Object (computer science)
In computer science, an object is any entity that can be manipulated by the commands of a programming language, such as a value, variable, function, or data structure...
, function, or variable
Variable (programming)
In computer programming, a variable is a symbolic name given to some known or unknown quantity or information, for the purpose of allowing the name to be used independently of the information it represents...
a call refers to without regard to the context of the call. In a hierarchical structure
Inheritance (object-oriented programming)
In object-oriented programming , inheritance is a way to reuse code of existing objects, establish a subtype from an existing object, or both, depending upon programming language support...
, a name is fully qualified when it "is complete in the sense that it includes (a) all names in the hierarchic sequence above the given element and (b) the name of the given element itself." Thus fully qualified names explicitly refer to namespace
Namespace
In general, a namespace is a container that provides context for the identifiers it holds, and allows the disambiguation of homonym identifiers residing in different namespaces....
s that would otherwise be implicit because of the scope
Scope (programming)
In computer programming, scope is an enclosing context where values and expressions are associated. Various programming languages have various types of scopes. The type of scope determines what kind of entities it can contain and how it affects them—or semantics...
of the call. While always done to eliminate ambiguity
Ambiguity
Ambiguity of words or phrases is the ability to express more than one interpretation. It is distinct from vagueness, which is a statement about the lack of precision contained or available in the information.Context may play a role in resolving ambiguity...
, this can mean different things dependent on context.
Commonly encountered applications of the notion have been given their own names, such as the fully qualified domain name and the fully qualified file name
Fully qualified file name
The term fully qualified file name means a file on a computer whose exact name is completely specified such that it is unambiguous and cannot be mistaken for any other file on that system. It is somewhat equivalent on the Internet to a URL specifying the full name of the computer and the entire...
.
Examples
To distinguish a fully qualified name from a regular name, C++C++
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
, Tcl
Tcl
Tcl is a scripting language created by John Ousterhout. Originally "born out of frustration", according to the author, with programmers devising their own languages intended to be embedded into applications, Tcl gained acceptance on its own...
, and Perl
Perl
Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...
use two colons (::), and Java
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
uses dots (.), as does Visual Basic .NET. and C#. In Java, ActionScript
ActionScript
ActionScript is an object-oriented language originally developed by Macromedia Inc. . It is a dialect of ECMAScript , and is used primarily for the development of websites and software targeting the Adobe Flash Player platform, used on Web pages in the form of...
, and other object-oriented languages the use of the dot is known as "dot syntax". Other examples include:
- As an example of a relational database, in Microsoft SQL ServerMicrosoft SQL ServerMicrosoft SQL Server is a relational database server, developed by Microsoft: It is a software product whose primary function is to store and retrieve data as requested by other software applications, be it those on the same computer or those running on another computer across a network...
the fully qualified name of an object is the one that specifies all four parts:server_name.[database_name].[schema_name].object_name.
- In PerlPerlPerl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...
, a fully qualified scalarScalar (computing)In computing, a scalar variable or field is one that can hold only one value at a time; as opposed to composite variables like array, list, hash, record, etc. In some contexts, a scalar value may be understood to be numeric. A scalar data type is the type of a scalar variable...
($scalar) that is in the packagepackage2would be referred to as$package2::scalar
- In UnixUnixUnix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
pathnamePath (computing)A path, the general form of a filename or of a directory name, specifies a unique location in a file system. A path points to a file system location by following the directory tree hierarchy expressed in a string of characters in which path components, separated by a delimiting character, represent...
s, instead of referring to./foo/bar/baz.shin/home/user/quz, which uses a relative pathname, the fully qualified name would be/home/user/quz/foo/bar/baz.shThis is an example of a fully qualified file nameFully qualified file nameThe term fully qualified file name means a file on a computer whose exact name is completely specified such that it is unambiguous and cannot be mistaken for any other file on that system. It is somewhat equivalent on the Internet to a URL specifying the full name of the computer and the entire...
.
- In the sense of domain nameDomain nameA domain name is an identification string that defines a realm of administrative autonomy, authority, or control in the Internet. Domain names are formed by the rules and procedures of the Domain Name System ....
s, a fully qualified domain name is explicitly suffixed with a dot, to eliminate the step of resolving, and to ensure that no additional suffix is added:wikipedia.com.for instance. This is an example of a fully qualified domain name.