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 | ||
| 7 | class LabelCollection implements \Countable | ||
| 8 | { | ||
| 9 | /** | ||
| 10 | * @var Label[] | ||
| 11 | */ | ||
| 12 | private $labels; | ||
| 13 | |||
| 14 | /** | ||
| 15 | * @param Label[] $labels | ||
| 16 | */ | ||
| 17 | public function __construct(array $labels = []) | ||
| 32 | |||
| 33 | /** | ||
| 34 | * @param Label $label | ||
| 35 | * @return LabelCollection | ||
| 36 | */ | ||
| 37 | public function with(Label $label) | ||
| 47 | |||
| 48 | /** | ||
| 49 | * @param Label $label | ||
| 50 | * @return LabelCollection | ||
| 51 | */ | ||
| 52 | View Code Duplication | public function without(Label $label) | |
| 63 | |||
| 64 | /** | ||
| 65 | * @inheritdoc | ||
| 66 | */ | ||
| 67 | public function count() | ||
| 71 | |||
| 72 | /** | ||
| 73 | * @param Label $label | ||
| 74 | * @return bool | ||
| 75 | */ | ||
| 76 | View Code Duplication | public function contains(Label $label) | |
| 87 | |||
| 88 | /** | ||
| 89 | * @return Label[] | ||
| 90 | */ | ||
| 91 | public function asArray() | ||
| 95 | |||
| 96 | /** | ||
| 97 | * @param LabelCollection $labelCollectionToMerge | ||
| 98 | * @return LabelCollection | ||
| 99 | */ | ||
| 100 | public function merge(LabelCollection $labelCollectionToMerge) | ||
| 118 | |||
| 119 | /** | ||
| 120 | * @param LabelCollection $labelCollection | ||
| 121 | * @return LabelCollection | ||
| 122 | */ | ||
| 123 | public function intersect(LabelCollection $labelCollection) | ||
| 134 | |||
| 135 | /** | ||
| 136 | * @param callable $filterFunction | ||
| 137 | * @return LabelCollection | ||
| 138 | */ | ||
| 139 | public function filter(callable $filterFunction) | ||
| 150 | |||
| 151 | /** | ||
| 152 | * @param string[] $strings | ||
| 153 | * @return LabelCollection | ||
| 154 | */ | ||
| 155 | public static function fromStrings(array $strings) | ||
| 169 | |||
| 170 | /** | ||
| 171 | * @param CultureFeed_Cdb_Data_Keyword[] $keywords | ||
| 172 | * @return LabelCollection | ||
| 173 | */ | ||
| 174 | public static function fromKeywords($keywords) | ||
| 188 | |||
| 189 | /** | ||
| 190 | * @return string[] | ||
| 191 | */ | ||
| 192 | public function toStrings() | ||
| 203 | } | ||
| 204 | 
Our type inference engine has found an assignment to a property that is incompatible with the declared type of that property.
Either this assignment is in error or the assigned type should be added to the documentation/type hint for that property..