| 1 | <?php | ||
| 14 | class Collection implements Countable, IteratorAggregate | ||
| 15 | { | ||
| 16 | |||
| 17 | /** | ||
| 18 | * @var array | ||
| 19 | */ | ||
| 20 | protected $data = array(); | ||
| 21 | |||
| 22 | /** | ||
| 23 | * Add to collection | ||
| 24 | * | ||
| 25 | * @param Model $model | ||
| 26 | */ | ||
| 27 | public function add(Model $model) | ||
| 31 | |||
| 32 | /** | ||
| 33 | * Get data as array | ||
| 34 | * | ||
| 35 | * @return array | ||
| 36 | */ | ||
| 37 | public function all() | ||
| 41 | |||
| 42 | /** | ||
| 43 | * Get data as array | ||
| 44 | * | ||
| 45 | * @return array | ||
| 46 | */ | ||
| 47 | public function data() | ||
| 51 | |||
| 52 | /** | ||
| 53 | * Collection count | ||
| 54 | * | ||
| 55 | * @return int|void | ||
| 56 | */ | ||
| 57 | public function count() | ||
| 61 | |||
| 62 | /** | ||
| 63 | * Get current | ||
| 64 | * | ||
| 65 | * @return Model | ||
| 66 | */ | ||
| 67 | public function current() | ||
| 71 | |||
| 72 | /** | ||
| 73 | * Get valid | ||
| 74 | * | ||
| 75 | * @return Model | ||
| 76 | */ | ||
| 77 | public function valid() | ||
| 81 | |||
| 82 | /** | ||
| 83 | * Get key | ||
| 84 | * | ||
| 85 | * @return Model | ||
| 86 | */ | ||
| 87 | public function key() | ||
| 91 | |||
| 92 | /** | ||
| 93 | * Get next | ||
| 94 | * | ||
| 95 | * @return Model | ||
| 96 | */ | ||
| 97 | public function next() | ||
| 101 | |||
| 102 | /** | ||
| 103 | * Get iterator | ||
| 104 | * | ||
| 105 | * @return ArrayIterator|Traversable | ||
| 106 | */ | ||
| 107 | public function getIterator() | ||
| 111 | } | ||
| 112 | 
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 implementation 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 interface: