principles:tell_don_t_ask_information_expert
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principles:tell_don_t_ask_information_expert [2013-02-18 17:24] – external edit 127.0.0.1 | principles:tell_don_t_ask_information_expert [2021-09-02 12:51] – old revision restored (2021-05-11 22:31) 65.21.179.175 | ||
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===== Caveats ===== | ===== Caveats ===== | ||
- | See section [[#contrary principles]]. | + | Sometimes assigning responsibilities using IE results in bas solutions (high coupling, low cohesion). This is because IE just focuses on the availability of data. So for example IE would demand domain objects saving themselves to the database. This is bad since it couples the domain objects to the database interface (JDBC, SQL, etc.) and lowers cohesion by adding unrelated responsibilities to the classes. Here it is better to give the task of persisting the domain objects to a separate class.((see Craig Larman: //Applying UML and Patterns – An Introduction to Object-Oriented Analysis and Design and Iterative Development//, |
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+ | See also section [[#contrary principles]]. | ||
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==== Generalizations ==== | ==== Generalizations ==== | ||
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- | * [[Low Coupling]] Adhering to the information expert principle leads to low coupling as there is less need to communicate with other modules to get the necessary information. | ||
- | * [[High Cohesion]] Adhering to information expert also means that a module only has responsibilities which belong together. So this increases cohesion. | ||
==== Specializations ==== | ==== Specializations ==== | ||
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==== Complementary Principles ==== | ==== Complementary Principles ==== | ||
+ | * [[Low Coupling]] Adhering to IE typically leads to low coupling as there is less need to communicate with other modules to get the necessary information. But in some cases IE also increases coupling (see [[# | ||
+ | * [[High Cohesion]] Adhering to IE typically leads to high cohesion as responsibilities which belong together typically operate on the same data. But in some cases IE also lowers cohesion (see [[# | ||
* [[Model Principle]] (MP): TdA/IE tells how to distribute functionality among the natural classes which are created according to the Model Principle. | * [[Model Principle]] (MP): TdA/IE tells how to distribute functionality among the natural classes which are created according to the Model Principle. | ||
* [[Information Hiding/ | * [[Information Hiding/ |
principles/tell_don_t_ask_information_expert.txt · Last modified: 2021-10-18 21:42 by christian