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{{short description|Network representation of the relationships between objects in a program}}

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In [[computer science]], in an [[Object-oriented programming|object-oriented program]], groups of [[Object (computer science)|objects]] form a network through their relationships with each other, either through a direct [[Reference (computer science)|reference]] to another object or through a chain of intermediate references. These groups of objects are referred to as '''object graphs''', after the mathematical objects called [[Graph (discrete mathematics)|graphs]] studied in [[graph theory]].

An '''Object Graph''' is a view of an object system at a particular point in time. Whereas a normal [[data model]] details the relationships between objects, the object graph relates the instances.

An '''Objectobject Graph'''graph is a view of an [[object system]] at a particular point in time. WhereasUnlike a normal [[data model]] such as a [[Unified Modeling Language]] (UML) [[class diagram]], which details the relationships between objects[[Class (computer programming)|classes]], the object graph relates thetheir [[Instance (computer science)|instances]]. [[Object diagram]]s are subsets of the overall object graph.

e.g. Instead of a car having a relationship to a wheel, MyCar has four relationships to four different Wheels (FrontLeft, FrontRight, BackLeft, BackRight).

Object graph is a term often used with object-oriented applications. Object-oriented applications contain complex webs of interrelated objects. Objects are linked to each other by one object either owning or containing another object or holding a reference to another object. This web of objects is called an object graph and it is the more abstract structure that can be used in discussing an application's state.

== Examples ==

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Object graph is a term often used with object-oriented applications. Object-oriented applications contain complex webs of interrelated objects. Objects are linked to each other by one object either owning or containing another object or holding a reference to another object. This web of objects is called an object graph.

==Physical representation==

Example: A → {B, C}, B → {D}, C → {A, D}, D → {B, A}.

An object graph is a [[directed graph]], which might be [[Cycle graph|cyclic]]. When stored in [[Random access memory|RAM]], objects occupy different segments of the memory with their attributes and function table, while relationships are represented by [[pointer (computer programming)|pointer]]s or a different type of global handler in higher-level languages.

== See also Examples==

For instance, a Car class can compose a Wheel one. In the object graph a Car instance will have up to four links to its wheels, which can be named frontLeft, frontRight, back Left and back Right.

An example of an [[adjacency list]] representation might be something as follows:

c:Car → {front Left:Wheel, front Right:Wheel, back Left:Wheel, back Right:Wheel}.

==See also==

* [[Data model]]

* [[Object diagram]]

{{DEFAULTSORT:Object Graph}}

[[Category:Data modeling diagrams]]

[[Category:Articles lacking sources (Erik9bot)]]