Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
| 1 | <?php | ||
| 26 | View Code Duplication | class Configuration implements ConfigurationInterface | |
| 27 | { | ||
| 28 | /** | ||
| 29 |      * {@inheritdoc} | ||
| 30 | */ | ||
| 31 | public function getConfigTreeBuilder() | ||
| 66 | } | ||
| 67 | 
Let’s take a look at an example:
In the above example, the authenticate() method works fine as long as you just pass instances of MyUser. However, if you now also want to pass a different sub-classes of User which does not have a getDisplayName() method, the code will break.
Available Fixes
Change the type-hint for the parameter:
Add an additional type-check:
Add the method to the parent class: