Creational pattern

In software engineering, creational design patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic form of object creation could result in design problems or in added complexity to the design. Creational design patterns solve this problem by somehow controlling this object creation.

Creational design patterns are composed of two dominant ideas. One is encapsulating knowledge about which concrete classes the system uses. Another is hiding how instances of these concrete classes are created and combined.[1]

Creational design patterns are further categorized into Object-creational patterns and Class-creational patterns, where Object-creational patterns deal with Object creation and Class-creational patterns deal with Class-instantiation. In greater details, Object-creational patterns defer part of its object creation to another object, while Class-creational patterns defer its object creation to subclasses.[2]

Five well-known design patterns that are parts of creational patterns are the

Definition

The creational patterns aim to separate a system from how its objects are created, composed, and represented. They increase the system's flexibility in terms of the what, who, how, and when of object creation.[6]

Usage

As modern software engineering depends more on object composition than class inheritance, emphasis shifts away from hard-coding behaviors toward defining a smaller set of basic behaviors that can be composed into more complex ones.[7] Hard-coding behaviors are inflexible because they require overriding or re-implementing the whole thing in order to change parts of the design. Additionally, hard-coding does not promote reuse and is hard to keep track of errors. For these reasons, creational patterns are more useful than hard-coding behaviors. Creational patterns make design become more flexible. They provide different ways to remove explicit references in the concrete classes from the code that needs to instantiate them.[8] In other words, they create independency for objects and classes.

Consider applying creational patterns when:

Structure

Creational Pattern class diagram.

Below is a simple class diagram that most creational patterns have in common. Note that different creational patterns require additional and different participated classes.

Participants:

Examples

Some examples of creational design patterns include:

See also

References

  1. Gamma, Erich; Helm, Richard; Johnson, Ralph; Vlissides, John (1995). Design Patterns. Massachusetts: Addison-Wesley. p. 81. ISBN 978-0-201-63361-0. Retrieved 2015-05-22.
  2. Gamma, Erich; Helm, Richard; Johnson, Ralph; Vlissides, John (1995). Design Patterns. Massachusetts: Addison-Wesley. ISBN 978-0-201-63361-0. Retrieved 2015-05-22.
  3. Freeman, Eric; Freeman, Elisabeth; Sierra, Kathy; Bates, Bert (2004). Hendrickson, Mike; Loukides, Mike, eds. Head First Design Patterns. California: O'Reilly Media. p. 156. ISBN 978-0-596-00712-6. Retrieved 2015-05-22.
  4. Freeman, Eric; Freeman, Elisabeth; Sierra, Kathy; Bates, Bert (2004). Hendrickson, Mike; Loukides, Mike, eds. Head First Design Patterns. California: O'Reilly Media. p. 134. ISBN 978-0-596-00712-6. Retrieved 2015-05-22.
  5. Freeman, Eric; Freeman, Elisabeth; Sierra, Kathy; Bates, Bert (2004). Hendrickson, Mike; Loukides, Mike, eds. Head First Design Patterns. California: O'Reilly Media. p. 177. ISBN 978-0-596-00712-6. Retrieved 2015-05-22.
  6. Judith, Bishop (2007). C# 3.0 Design Patterns. California: O'Reilly Media. p. 336. ISBN 978-0-596-52773-0. Retrieved 2015-05-22.
  7. Gamma, Erich; Helm, Richard; Johnson, Ralph; Vlissides, John (1995). Design Patterns. Massachusetts: Addison-Wesley. p. 84. ISBN 978-0-201-63361-0. Retrieved 2015-05-22.
  8. Gamma, Erich; Helm, Richard; Johnson, Ralph; Vlissides, John (1995). Design Patterns. Massachusetts: Addison-Wesley. p. 85. ISBN 978-0-201-63361-0. Retrieved 2015-05-22.
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