Dependency inversion principle

In object-oriented programming, the dependency inversion principle refers to a specific form of decoupling software modules.

Description

When following this principle, the conventional dependency relationships established from high-level, policy-setting modules to low-level, dependency modules are reversed, thus rendering high-level modules independent of the low-level module implementation details. The principle states:

• A. High-level modules should not depend on low-level modules. Both should depend on abstractions.
• B. Abstractions should not depend on details. Details should depend on abstractions.

The principle inverts the way some people may think about object-oriented design, dictating that both high- and low-level objects must depend on the same abstraction.

See also

• Abstraction (software engineering)
• Adapter pattern
• Coupling (computer programming)
• Creational pattern
• Dependency Injection
• Design by contract
• Interface
• Inversion of Control
• Modular programming
• Object-oriented programming
• Plug-in (computing)
• Service locator pattern
• SOLID – the "D" in "SOLID" stands for the dependency inversion principle

External links

• Dependency inversion principle @ Wikipedia