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 |
||
27 | class PasswordRepository implements PasswordRepositoryInterface |
||
28 | { |
||
29 | const EXPIRED_PASSWORDS_PURGE_SIZE = 60000; |
||
30 | |||
31 | /** |
||
32 | * @var PasswordFactory |
||
33 | */ |
||
34 | private $passwordFactory; |
||
35 | |||
36 | /** |
||
37 | * @var PasswordResource |
||
38 | */ |
||
39 | private $passwordResource; |
||
40 | |||
41 | /** |
||
42 | * @var CollectionFactory |
||
43 | */ |
||
44 | private $collectionFactory; |
||
45 | |||
46 | /** |
||
47 | * PasswordRepository constructor. |
||
48 | * @param PasswordFactory $passwordFactory |
||
49 | * @param PasswordResource $passwordResource |
||
50 | * @param CollectionFactory $collectionFactory |
||
51 | */ |
||
52 | public function __construct( |
||
61 | |||
62 | /** |
||
63 | * @param int $customerId |
||
64 | * @return PasswordInterface |
||
65 | * @throws NoSuchEntityException |
||
66 | */ |
||
67 | View Code Duplication | public function getByCustomerId(int $customerId): PasswordInterface |
|
77 | |||
78 | /** |
||
79 | * @param PasswordInterface $password |
||
80 | * @return void |
||
81 | * @throws Exception |
||
82 | */ |
||
83 | public function save(PasswordInterface $password): void |
||
97 | |||
98 | /** |
||
99 | * @param PasswordInterface $password |
||
100 | * @return void |
||
101 | * @throws Exception |
||
102 | */ |
||
103 | View Code Duplication | public function delete(PasswordInterface $password): void |
|
114 | |||
115 | /** |
||
116 | * @param string $dateTime |
||
117 | * @return PasswordInterface[] |
||
118 | */ |
||
119 | public function getOlderThan(string $dateTime): array |
||
132 | } |
||
133 |
Let’s assume that you have a directory layout like this:
and let’s assume the following content of
Bar.php
:If both files
OtherDir/Foo.php
andSomeDir/Foo.php
are loaded in the same runtime, you will see a PHP error such as the following:PHP Fatal error: Cannot use SomeDir\Foo as Foo because the name is already in use in OtherDir/Foo.php
However, as
OtherDir/Foo.php
does not necessarily have to be loaded and the error is only triggered if it is loaded beforeOtherDir/Bar.php
, this problem might go unnoticed for a while. In order to prevent this error from surfacing, you must import the namespace with a different alias: