Attribute (computing)

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In computing, an attribute is a specification that defines a property of an object, element, or file. It may also refer to or set the specific value for a given instance of such.

However, in actual usage, the term attribute can and is often treated as equivalent to a property depending on the technology being discussed.

For clarity, attributes should more correctly be considered metadata. An attribute is frequently and generally a property of a property.

A good example is the process of XML assigning values to properties (elements). Note the element's value is found before the (separate) end tag, not in the element itself. The element itself may have a number of attributes set (NAME="IAMAPROPERTY").

If the element in question could be considered a property (CUSTOMER_NAME) of another entity (lets say CUSTOMER), the element can have zero or more attributes (properties) of its own (CUSTOMER_NAME is of TYPE="KINDOFTEXT").

An attribute of an object usually consists of a name and a value; of an element, a type or class name; of a file, a name and extension.

Each named attribute has an associated set of rules called operations: one doesn't add characters or manipulate and process an integer array as an image object— one doesn't process text as type floating point (decimal numbers).

It follows that an object definition can be extended by imposing data typing: a representation format, a default value, and legal operations (rules) and restrictions ("Division by zero is not to be tolerated!") are all potentially involved in defining an attribute, or conversely, may be spoken of as attributes of that object's type. A JPEG file is not decoded by the same operations (however similar they may be—these are all graphics data formats) as a PNG or BMP file, nor is a floating point typed number operated upon by the rules applied to typed long integers.

For example, in computer graphics, line objects can have attributes such as thickness (with real values), color (with descriptive values such as brown or green or values defined in a certain color model, such as RGB), dashing attributes, etc. A circle object can be defined in similar attributes plus an origin and radius.

Markup languages, such as HTML and XML, use attributes to describe data and the formatting of data.

Attributes in C#

In the C# programming language, attributes are metadata attached to a field or a block of code, equivalent to annotations in Java.

Attributes in post-relational databases

On many post-relational databases systems, relative to SQL, columns are attributes, rows are records, and tables are files.

Attribute (computing)

Attributes in C#

Attributes in post-relational databases

See also