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:
Complex classes like Legacy_Storage_Service often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use Legacy_Storage_Service, and based on these observations, apply Extract Interface, too.
1 | <?php |
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16 | class Legacy_Storage_Service extends Service { |
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17 | |||
18 | /** |
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19 | * Contaier repository to fetch fields from |
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20 | * |
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21 | * @var ContainerRepository |
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22 | */ |
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23 | protected $container_repository; |
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24 | |||
25 | /** |
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26 | * Key Toolset for key generation and comparison utilities |
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27 | * |
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28 | * @var Key_Toolset |
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29 | */ |
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30 | protected $key_toolset; |
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31 | |||
32 | /** |
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33 | * List of special key suffixes that the Map field uses so save extra data |
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34 | * |
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35 | * @var array |
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36 | */ |
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37 | protected $map_keys = array( 'lat', 'lng', 'zoom', 'address' ); |
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38 | |||
39 | /** |
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40 | * Cache of converted storage arrays |
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41 | * |
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42 | * @var array |
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43 | */ |
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44 | protected $storage_array_cache = array(); |
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45 | |||
46 | /** |
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47 | * Service constructor |
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48 | * |
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49 | * @param ContainerRepository $container_repository |
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50 | */ |
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51 | public function __construct( ContainerRepository $container_repository, Key_Toolset $key_toolset ) { |
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55 | |||
56 | /** |
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57 | * Enable the service |
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58 | */ |
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59 | protected function enabled() { |
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62 | |||
63 | /** |
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64 | * Disable the service |
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65 | */ |
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66 | protected function disabled() { |
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69 | |||
70 | /** |
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71 | * Check if a key is a legacy map property key |
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72 | * |
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73 | * @param string $key |
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74 | * @return bool |
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75 | */ |
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76 | protected function is_legacy_map_key( $key ) { |
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77 | $map_regex = array_map( function( $map_key ) { |
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78 | return preg_quote( $map_key, '/' ); |
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79 | }, $this->map_keys ); |
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80 | $map_regex = '/-(' . implode( '|', $map_regex ) . ')$/'; |
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81 | return (bool) preg_match( $map_regex, $key ); |
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82 | } |
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83 | |||
84 | /** |
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85 | * Return container instance which uses the passed datastore |
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86 | * |
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87 | * @param Datastore_Interface $datastore |
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88 | * @return Container |
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89 | */ |
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90 | protected function get_container_for_datastore( Datastore_Interface $datastore ) { |
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91 | $containers = $this->container_repository->get_containers(); |
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92 | foreach ( $containers as $container ) { |
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93 | if ( $container->get_datastore() === $datastore ) { |
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94 | return $container; |
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95 | } |
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96 | } |
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97 | return null; |
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98 | } |
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99 | |||
100 | /** |
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101 | * Get a nested array of field_group permutations suitable for old key parsing |
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102 | * |
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103 | * @param array $fields |
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104 | * @return array |
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105 | */ |
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106 | protected function get_field_group_permutations( $fields ) { |
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107 | $permutations = array(); |
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108 | |||
109 | foreach ( $fields as $field ) { |
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110 | if ( is_a( $field, 'Carbon_Fields\\Field\\Complex_Field' ) ) { |
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111 | $group_names = $field->get_group_names(); |
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112 | foreach ( $group_names as $group_name ) { |
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113 | $group = $field->get_group_by_name( $group_name ); |
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114 | if ( ! $group ) { |
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115 | continue; |
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116 | } |
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117 | $permutations[] = array( |
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118 | 'field' => $field->get_base_name(), |
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119 | 'group' => $group_name, |
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120 | 'children' => $this->get_field_group_permutations( $group->get_fields() ), |
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121 | ); |
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122 | } |
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123 | } else { |
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124 | $permutations[] = array( |
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125 | 'field' => $field->get_base_name(), |
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126 | 'group' => '', |
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127 | 'children' => array(), |
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128 | ); |
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129 | } |
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130 | } |
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131 | |||
132 | return $permutations; |
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133 | } |
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134 | |||
135 | /** |
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136 | * Get array of database table details for datastore |
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137 | * |
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138 | * @param Datastore_Interface $datastore |
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139 | * @return array |
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140 | */ |
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141 | protected function get_table_details_for_datastore( Datastore_Interface $datastore ) { |
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166 | |||
167 | /** |
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168 | * Get array of sql comparisons for field |
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169 | * |
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170 | * @param Field $field |
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171 | * @param string $key_prefix |
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172 | * @param string $key_column |
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173 | * @return array<string> |
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174 | */ |
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175 | protected function get_legacy_sql_comparisons_for_field( Field $field, $key_prefix, $key_column ) { |
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197 | |||
198 | /** |
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199 | * Get a key-value array of legacy values for fields in the container of the passed datastore |
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200 | * |
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201 | * @param Container $container |
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202 | * @return array |
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203 | */ |
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204 | protected function get_legacy_storage_array_from_database( Container $container ) { |
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243 | |||
244 | /** |
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245 | * Get a key-value array of CF 1.5 values for fields in the container of the passed datastore |
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246 | * |
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247 | * @param Datastore_Interface $datastore |
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248 | * @return array |
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249 | */ |
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250 | public function get_legacy_storage_array( Datastore_Interface $datastore ) { |
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262 | |||
263 | /** |
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264 | * Get expanded value for key from legacy storage array |
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265 | * |
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266 | * @param string $key Legacy key to fetch additional values for |
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267 | * @param array $legacy_storage_array key=>value array of legacy data |
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268 | * @return mixed |
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269 | */ |
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270 | protected function get_value_for_legacy_key( $key, $legacy_storage_array ) { |
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286 | |||
287 | /** |
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288 | * Convert legacy storage rows to array of row descriptors |
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289 | * |
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290 | * @param array $legacy_storage_array |
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291 | * @param array $field_group_permutations |
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292 | * @return array |
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293 | */ |
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294 | protected function legacy_storage_rows_to_row_descriptors( $legacy_storage_array, $field_group_permutations ) { |
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308 | |||
309 | /** |
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310 | * Get key segmentation regex for a field name |
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311 | * |
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312 | * @param string $field_name |
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313 | * @param string $group_name |
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314 | * @return string |
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315 | */ |
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316 | protected function get_key_segmentation_regex_for_field_name( $field_name, $group_name = '' ) { |
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325 | |||
326 | /** |
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327 | * Convert legacy storage row to row descriptor |
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328 | * |
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329 | * @param string $key |
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330 | * @param string $value |
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331 | * @param array $field_group_permutations |
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332 | * @return array |
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333 | */ |
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334 | protected function legacy_storage_row_to_row_descriptor( $key, $value, $field_group_permutations ) { |
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369 | |||
370 | /** |
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371 | * Convert row descriptor to array of new storage key-values |
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372 | * |
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373 | * @param array $row_descriptor |
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374 | * @return array |
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375 | */ |
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376 | protected function row_descriptor_to_storage_array( $row_descriptor ) { |
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431 | |||
432 | /** |
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433 | * Get all data saved for a datastore in the new key-value format |
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434 | * |
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435 | * @param Datastore_Interface $datastore |
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436 | * @return array |
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437 | */ |
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438 | 1 | public function get_storage_array_for_datastore( Datastore_Interface $datastore ) { |
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455 | |||
456 | /** |
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457 | * Get array of new storage key-values matching key patterns |
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458 | * |
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459 | * @param Datastore_Interface $datastore |
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460 | * @param array $storage_key_patterns |
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461 | * @return array |
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462 | */ |
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463 | 1 | public function get_storage_array( Datastore_Interface $datastore, $storage_key_patterns ) { |
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476 | |||
477 | public function filter_storage_array( $storage_array, $datastore, $storage_key_patterns ) { |
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483 | } |
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: