Efferent coupling is a
coupling metric in
software development
Software development is the process of conceiving, specifying, designing, programming, documenting, testing, and bug fixing involved in creating and maintaining applications, frameworks, or other software components. Software development invol ...
. It measures the number of
data type
In computer science and computer programming, a data type (or simply type) is a set of possible values and a set of allowed operations on it. A data type tells the compiler or interpreter how the programmer intends to use the data. Most progra ...
s a
class knows about.
This includes
inheritance, interface implementation, parameter types, variable types, and
exceptions.
This has also been referred to by
Robert C. Martin as the Fan-out stability metric which in his book Clean Architecture he describes as Outgoing dependencies. This metric identifies the number of classes inside this component that depend on classes outside the component.
This metric is often used to calculate instability of a component in
software architecture as ''I'' = Fan-out / (Fan-in + Fan-out). This metric has a range
,1 ''I'' = 0 is maximally stable while ''I'' = 1 is maximally unstable.
References
Software metrics
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