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 TelegramLog 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 TelegramLog, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 36 | class TelegramLog |
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| 37 | { |
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| 38 | /** |
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| 39 | * Logger instance |
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| 40 | * |
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| 41 | * @var LoggerInterface|Logger |
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| 42 | */ |
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| 43 | protected static $logger; |
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| 44 | |||
| 45 | /** |
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| 46 | * Logger instance for update |
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| 47 | * |
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| 48 | * @var LoggerInterface|Logger |
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| 49 | */ |
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| 50 | protected static $update_logger; |
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| 51 | |||
| 52 | /** |
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| 53 | * Path for error log |
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| 54 | * |
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| 55 | * @var string |
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| 56 | * @deprecated |
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| 57 | */ |
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| 58 | protected static $error_log_path; |
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| 59 | |||
| 60 | /** |
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| 61 | * Path for debug log |
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| 62 | * |
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| 63 | * @var string |
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| 64 | * @deprecated |
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| 65 | */ |
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| 66 | protected static $debug_log_path; |
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| 67 | |||
| 68 | /** |
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| 69 | * Path for update log |
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| 70 | * |
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| 71 | * @var string |
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| 72 | * @deprecated |
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| 73 | */ |
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| 74 | protected static $update_log_path; |
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| 75 | |||
| 76 | /** |
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| 77 | * Temporary stream handle for debug log |
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| 78 | * |
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| 79 | * @var resource|null |
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| 80 | */ |
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| 81 | protected static $debug_log_temp_stream_handle; |
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| 82 | |||
| 83 | /** |
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| 84 | * Initialise Logger instance, optionally passing an existing one. |
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| 85 | * |
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| 86 | * @param LoggerInterface|null $logger |
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| 87 | * @param LoggerInterface|null $update_logger |
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| 88 | */ |
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| 89 | public static function initialize(LoggerInterface $logger = null, LoggerInterface $update_logger = null) |
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| 110 | |||
| 111 | /** |
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| 112 | * Initialise error log (deprecated) |
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| 113 | * |
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| 114 | * @param string $path |
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| 115 | * |
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| 116 | * @return LoggerInterface |
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| 117 | * @throws Exception |
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| 118 | * |
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| 119 | * @deprecated Initialise a preconfigured logger instance instead. |
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| 120 | */ |
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| 121 | View Code Duplication | public static function initErrorLog($path) |
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| 142 | |||
| 143 | /** |
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| 144 | * Initialise debug log (deprecated) |
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| 145 | * |
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| 146 | * @param string $path |
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| 147 | * |
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| 148 | * @return LoggerInterface |
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| 149 | * @throws Exception |
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| 150 | * |
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| 151 | * @deprecated Initialise a preconfigured logger instance instead. |
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| 152 | */ |
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| 153 | View Code Duplication | public static function initDebugLog($path) |
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| 174 | |||
| 175 | /** |
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| 176 | * Initialise update log (deprecated) |
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| 177 | * |
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| 178 | * @param string $path |
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| 179 | * |
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| 180 | * @return LoggerInterface |
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| 181 | * @throws Exception |
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| 182 | * |
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| 183 | * @deprecated Initialise a preconfigured logger instance instead. |
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| 184 | */ |
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| 185 | public static function initUpdateLog($path) |
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| 205 | |||
| 206 | /** |
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| 207 | * Get the stream handle of the temporary debug output |
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| 208 | * |
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| 209 | * @return mixed The stream if debug is active, else false |
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| 210 | */ |
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| 211 | public static function getDebugLogTempStream() |
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| 219 | |||
| 220 | /** |
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| 221 | * Write the temporary debug stream to log and close the stream handle |
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| 222 | * |
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| 223 | * @param string $message Message (with placeholder) to write to the debug log |
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| 224 | */ |
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| 225 | public static function endDebugLogTempStream($message = '%s') |
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| 234 | |||
| 235 | /** |
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| 236 | * Is error log active |
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| 237 | * |
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| 238 | * @return bool |
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| 239 | * |
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| 240 | * @deprecated Initialise a preconfigured logger instance instead. |
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| 241 | */ |
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| 242 | public static function isErrorLogActive() |
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| 247 | |||
| 248 | /** |
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| 249 | * Is debug log active |
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| 250 | * |
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| 251 | * @return bool |
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| 252 | * |
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| 253 | * @deprecated Initialise a preconfigured logger instance instead. |
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| 254 | */ |
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| 255 | public static function isDebugLogActive() |
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| 260 | |||
| 261 | /** |
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| 262 | * Is update log active |
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| 263 | * |
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| 264 | * @return bool |
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| 265 | * |
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| 266 | * @deprecated Initialise a preconfigured logger instance instead. |
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| 267 | */ |
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| 268 | public static function isUpdateLogActive() |
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| 273 | |||
| 274 | /** |
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| 275 | * Handle any logging method call. |
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| 276 | * |
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| 277 | * @param string $name |
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| 278 | * @param array $arguments |
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| 279 | */ |
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| 280 | public static function __callStatic($name, array $arguments) |
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| 307 | |||
| 308 | /** |
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| 309 | * Interpolates context values into the message placeholders. |
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| 310 | * |
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| 311 | * @see https://www.php-fig.org/psr/psr-3/#12-message |
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| 312 | * |
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| 313 | * @param string $message |
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| 314 | * @param array $context |
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| 315 | * |
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| 316 | * @return string |
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| 317 | */ |
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| 318 | protected static function interpolate($message, array $context = []) |
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| 332 | } |
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| 333 |
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: