What is "dependency inversion principle"

n. (context programming object-oriented English) Design principle that states that (1) High- and low-level modules should both depend on abstractions and (2) instead of abstractions depending upon details, details should depend upon abstractions.

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

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.