Complex classes like FileCache 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 FileCache, and based on these observations, apply Extract Interface, too.
| 1 | <?php | ||
| 22 | class FileCache implements CacheInterface, CounterInterface | ||
| 23 | { | ||
| 24 | // TODO garbage collection | ||
| 25 | |||
| 26 | /** | ||
| 27 | * @var string control characters for keys, reserved by PSR-16 | ||
| 28 | */ | ||
| 29 |     const PSR16_RESERVED = '/\{|\}|\(|\)|\/|\\\\|\@|\:/u'; | ||
| 30 | |||
| 31 | /** | ||
| 32 | * @var string | ||
| 33 | */ | ||
| 34 | private $cache_path; | ||
| 35 | |||
| 36 | /** | ||
| 37 | * @var int | ||
| 38 | */ | ||
| 39 | private $default_ttl; | ||
| 40 | |||
| 41 | /** | ||
| 42 | * @param string $cache_path absolute root path of cache-file folder | ||
| 43 | * @param int $default_ttl default time-to-live (in seconds) | ||
| 44 | * | ||
| 45 | * @throws InvalidArgumentException if the specified cache-path does not exist (or is not writable) | ||
| 46 | */ | ||
| 47 | public function __construct($cache_path, $default_ttl) | ||
| 62 | |||
| 63 | public function get($key, $default = null) | ||
| 97 | |||
| 98 | public function set($key, $value, $ttl = null) | ||
| 132 | |||
| 133 | public function delete($key) | ||
| 137 | |||
| 138 | public function clear() | ||
| 146 | |||
| 147 | public function getMultiple($keys) | ||
| 157 | |||
| 158 | public function setMultiple($items, $ttl = null) | ||
| 168 | |||
| 169 | public function deleteMultiple($keys) | ||
| 175 | |||
| 176 | public function has($key) | ||
| 180 | |||
| 181 | public function increment($key, $step = 1) | ||
| 205 | |||
| 206 | public function decrement($key, $step = 1) | ||
| 210 | |||
| 211 | /** | ||
| 212 | * Clean up expired cache-files. | ||
| 213 | * | ||
| 214 | * This method is outside the scope of the PSR-16 cache concept, and is specific to | ||
| 215 | * this implementation, being a file-cache. | ||
| 216 | * | ||
| 217 | * In scenarios with dynamic keys (such as Session IDs) you should call this method | ||
| 218 | * periodically - for example from a scheduled daily cron-job. | ||
| 219 | * | ||
| 220 | * @return void | ||
| 221 | */ | ||
| 222 | public function cleanExpired() | ||
| 234 | |||
| 235 | /** | ||
| 236 | * For a given cache key, obtain the absolute file path | ||
| 237 | * | ||
| 238 | * @param string $key | ||
| 239 | * | ||
| 240 | * @return string absolute path to cache-file | ||
| 241 | * | ||
| 242 | * @throws InvalidArgumentException if the specified key contains a character reserved by PSR-16 | ||
| 243 | */ | ||
| 244 | protected function getPath($key) | ||
| 260 | |||
| 261 | /** | ||
| 262 | * @return int current timestamp | ||
| 263 | */ | ||
| 264 | protected function getTime() | ||
| 268 | |||
| 269 | /** | ||
| 270 | * @return Generator|string[] | ||
| 271 | */ | ||
| 272 | protected function listPaths() | ||
| 289 | } | ||
| 290 | 
If you suppress an error, we recommend checking for the error condition explicitly: