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  | 
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| 16 | class Projector implements EventListenerInterface  | 
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| 17 | { | 
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| 18 | use DelegateEventHandlingToSpecificMethodTrait;  | 
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| 19 | |||
| 20 | /**  | 
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| 21 | * @var RepositoryInterface  | 
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| 22 | */  | 
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| 23 | private $repository;  | 
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| 24 | |||
| 25 | /**  | 
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| 26 | * @var SapiVersion  | 
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| 27 | */  | 
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| 28 | private $sapiVersion;  | 
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| 29 | |||
| 30 | /**  | 
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| 31 | * @param RepositoryInterface $repository  | 
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| 32 | * @param SapiVersion $sapiVersion  | 
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| 33 | */  | 
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| 34 | public function __construct(  | 
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| 40 | |||
| 41 | /**  | 
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| 42 | * @param RoleCreated $roleCreated  | 
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| 43 | * @param DomainMessage $domainMessage  | 
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| 44 | */  | 
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| 45 | public function applyRoleCreated(  | 
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| 54 | |||
| 55 | /**  | 
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| 56 | * @param RoleRenamed $roleRenamed  | 
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| 57 | * @param DomainMessage $domainMessage  | 
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| 58 | */  | 
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| 59 | public function applyRoleRenamed(  | 
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| 68 | |||
| 69 | /**  | 
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| 70 | * @param RoleDeleted $roleDeleted  | 
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| 71 | * @param DomainMessage $domainMessage  | 
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| 72 | */  | 
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| 73 | public function applyRoleDeleted(  | 
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| 79 | |||
| 80 | /**  | 
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| 81 | * @param ConstraintAdded $constraintAdded  | 
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| 82 | */  | 
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| 83 | View Code Duplication |     protected function applyConstraintAdded(ConstraintAdded $constraintAdded) { | 
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| 92 | |||
| 93 | /**  | 
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| 94 | * @param ConstraintUpdated $constraintUpdated  | 
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| 95 | */  | 
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| 96 | View Code Duplication | protected function applyConstraintUpdated(ConstraintUpdated $constraintUpdated)  | 
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| 106 | |||
| 107 | /**  | 
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| 108 | * @param ConstraintRemoved $constraintRemoved  | 
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| 109 | */  | 
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| 110 | protected function applyConstraintRemoved(ConstraintRemoved $constraintRemoved)  | 
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| 119 | }  | 
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| 120 | 
This check looks from parameters that have been defined for a function or method, but which are not used in the method body.