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<overview>

<p>

Efferent coupling is the number of outgoing dependencies for each module. In other words, it is the

number of other modules on which each module depends.

</p>

<p>

A module that depends on many other modules is quite brittle, because if any of

its dependencies change, the module itself may have to change as well. Furthermore, the

reason for the high number of dependencies is often that different parts of

the module depend on different groups of other modules, so it is common to

find that modules with high efferent coupling also lack cohesion.

</p>

</overview>

<recommendation>

<p>

You can reduce efferent coupling by splitting up a module so that each part depends on fewer modules.

</p>

</recommendation>

<references>

<li>

IBM developerWorks: <a href="https://web.archive.org/web/20190919085934/https://www.ibm.com/developerworks/library/j-eaed6/">Evolutionary architecture and emergent design: Emergent design through metrics</a>.

</li>

<li>

R. Martin, <em>Agile Software Development: Principles, Patterns and Practices</em>. Pearson, 2011.

</li>

</references>

</qhelp>