CSC/ECE 517 Fall 2010/ch7 7b JB: Difference between revisions

From Expertiza_Wiki
Jump to navigation Jump to search
No edit summary
 
No edit summary
Line 1: Line 1:
=Information Expert Pattern=
=Information Expert Pattern=
==Introduction==
Information Expert Pattern is a principle for assigning responsibility in object-oriented design.  The fundamental idea is to identify the class with the most information (expertise) and assign responsibility to it.
==GRASP==
In object-oriented design, the overall problems of assigning responsibility are dealt with by GRASP[http://en.wikipedia.org/wiki/GRASP_%28object-oriented_design%29], or General Responsibility Assignment Software Patterns (or Principles). GRASP has nine principles, of which Information Expert is one. The others are:
#Creator [http://en.wikipedia.org/wiki/GRASP_%28object-oriented_design%29#Creator]
#Low Coupling [http://en.wikipedia.org/wiki/GRASP_%28object-oriented_design%29#Low_Coupling]
#High Cohesion [http://en.wikipedia.org/wiki/GRASP_%28object-oriented_design%29#High_Cohesion]
#Controller [http://en.wikipedia.org/wiki/GRASP_%28object-oriented_design%29#Controller]
#Polymorphysm [http://en.wikipedia.org/wiki/GRASP_%28object-oriented_design%29#Polymorphism]
#Pure Fabrication [http://en.wikipedia.org/wiki/GRASP_%28object-oriented_design%29#Pure_Fabrication]
#Indirection [http://en.wikipedia.org/wiki/GRASP_%28object-oriented_design%29#Indirection]
#Protected Variations [http://en.wikipedia.org/wiki/GRASP_%28object-oriented_design%29#Protected_Variations]
==Process==
Using this approach, the programmer would:
# Identify a responsibility
# Determine what information is needed to fulfill it,
# Locate where that information is stored
# Identify which class contains the largest subset of the required data
# Assign responsibility to that class
# Assign the responsible class to recursively apply the Information Expert Pattern for acquiring any data still missing.
==References==
# [http://en.wikipedia.org/wiki/GRASP_%28object-oriented_design%29 Wikipedia's GRASP article]
# [http://cs.armstrong.edu/hsu/Course/CSCI3321/PracticalSoftwareEngineering/html/ch10s04.html Information Expert Pattern overview with diagrams]
# [http://programmersnotes.info/2009/03/28/creator-and-information-expert-grasp-design-pattern-series/#expert Creator and Information Expert Principles with sample code]

Revision as of 06:16, 2 December 2010

Information Expert Pattern

Introduction

Information Expert Pattern is a principle for assigning responsibility in object-oriented design. The fundamental idea is to identify the class with the most information (expertise) and assign responsibility to it.


GRASP

In object-oriented design, the overall problems of assigning responsibility are dealt with by GRASP[1], or General Responsibility Assignment Software Patterns (or Principles). GRASP has nine principles, of which Information Expert is one. The others are:

  1. Creator [2]
  2. Low Coupling [3]
  3. High Cohesion [4]
  4. Controller [5]
  5. Polymorphysm [6]
  6. Pure Fabrication [7]
  7. Indirection [8]
  8. Protected Variations [9]


Process

Using this approach, the programmer would:

  1. Identify a responsibility
  2. Determine what information is needed to fulfill it,
  3. Locate where that information is stored
  4. Identify which class contains the largest subset of the required data
  5. Assign responsibility to that class
  6. Assign the responsible class to recursively apply the Information Expert Pattern for acquiring any data still missing.


References

  1. Wikipedia's GRASP article
  2. Information Expert Pattern overview with diagrams
  3. Creator and Information Expert Principles with sample code
Retrieved from "https://wiki.expertiza.ncsu.edu/index.php?title=CSC/ECE_517_Fall_2010/ch7_7b_JB&oldid=43320"