CSC/ECE 517 Fall 2009/wiki3 5 SD: Difference between revisions
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Dependency inversion principle states that: | Dependency inversion principle states that: | ||
<ol> | <ol> | ||
<li>High-level modules should not depend on low-level modules. Both should depend on abstractions.</ | <li>High-level modules should not depend on low-level modules. Both should depend on abstractions.</li> | ||
<li>Abstractions should not depend upon details. Details should depend upon abstractions.</ | <li>Abstractions should not depend upon details. Details should depend upon abstractions.</li> | ||
</ol> | </ol> | ||
Revision as of 14:52, 14 November 2009
Dependency inversion principle
Dependency inversion principle states that:
- High-level modules should not depend on low-level modules. Both should depend on abstractions.
- Abstractions should not depend upon details. Details should depend upon abstractions.
Introduction
In conventional application architecture, lower-level components are designed to be consumed by higher-level components which enable increasingly complex systems to be built. In this composition, higher-level components depend directly upon lower-level components to achieve some task. This dependency upon lower-level components makes applications rigid, fragile and immobile.