Complex classes like Interval 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 Interval, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 57 | class Interval extends DateInterval  | 
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| 58 | { | 
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| 59 | use DateLocalizationCapabilities;  | 
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| 60 | /**  | 
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| 61 | * Interval spec period designators.  | 
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| 62 | */  | 
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| 63 | const PERIOD_PREFIX = 'P';  | 
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| 64 | const PERIOD_YEARS = 'Y';  | 
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| 65 | const PERIOD_MONTHS = 'M';  | 
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| 66 | const PERIOD_DAYS = 'D';  | 
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| 67 | const PERIOD_TIME_PREFIX = 'T';  | 
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| 68 | const PERIOD_HOURS = 'H';  | 
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| 69 | const PERIOD_MINUTES = 'M';  | 
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| 70 | const PERIOD_SECONDS = 'S';  | 
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| 71 | |||
| 72 | /**  | 
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| 73 | * Before PHP 5.4.20/5.5.4 instead of FALSE days will be set to -99999 when the interval instance  | 
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| 74 | * was created by DateTime:diff().  | 
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| 75 | */  | 
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| 76 | const PHP_DAYS_FALSE = -99999;  | 
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| 77 | |||
| 78 | /**  | 
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| 79 | * Determine if the interval was created via DateTime:diff() or not.  | 
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| 80 | *  | 
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| 81 | * @param DateInterval $interval  | 
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| 82 | *  | 
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| 83 | * @return bool  | 
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| 84 | */  | 
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| 85 | private static function wasCreatedFromDiff(DateInterval $interval)  | 
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| 89 | |||
| 90 | ///////////////////////////////////////////////////////////////////  | 
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| 91 | //////////////////////////// CONSTRUCTORS /////////////////////////  | 
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| 92 | ///////////////////////////////////////////////////////////////////  | 
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| 93 | |||
| 94 | /**  | 
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| 95 | * Create a new Interval instance.  | 
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| 96 | *  | 
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| 97 | * @param int $years  | 
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| 98 | * @param int $months  | 
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| 99 | * @param int $weeks  | 
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| 100 | * @param int $days  | 
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| 101 | * @param int $hours  | 
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| 102 | * @param int $minutes  | 
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| 103 | * @param int $seconds  | 
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| 104 | */  | 
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| 105 | public function __construct(  | 
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| 139 | |||
| 140 | /**  | 
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| 141 | * Create a new Interval instance from specific values.  | 
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| 142 | * This is an alias for the constructor that allows better fluent  | 
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| 143 | * syntax as it allows you to do Interval::create(1)->fn() rather than  | 
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| 144 | * (new Interval(1))->fn().  | 
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| 145 | *  | 
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| 146 | * @param int $years  | 
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| 147 | * @param int $months  | 
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| 148 | * @param int $weeks  | 
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| 149 | * @param int $days  | 
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| 150 | * @param int $hours  | 
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| 151 | * @param int $minutes  | 
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| 152 | * @param int $seconds  | 
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| 153 | *  | 
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| 154 | * @return static  | 
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| 155 | */  | 
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| 156 | public static function create(  | 
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| 167 | |||
| 168 | /**  | 
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| 169 | * Provide static helpers to create instances. Allows Interval::years(3).  | 
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| 170 | *  | 
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| 171 | * Note: This is done using the magic method to allow static and instance methods to  | 
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| 172 | * have the same names.  | 
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| 173 | *  | 
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| 174 | * @param string $name  | 
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| 175 | * @param array $args  | 
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| 176 | *  | 
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| 177 | * @return static  | 
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| 178 | */  | 
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| 179 | public static function __callStatic($name, $args)  | 
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| 216 | |||
| 217 | /**  | 
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| 218 | * Create a Interval instance from a DateInterval one. Can not instance  | 
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| 219 | * Interval objects created from DateTime::diff() as you can't externally  | 
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| 220 | * set the $days field.  | 
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| 221 | *  | 
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| 222 | * @param DateInterval|Interval $di  | 
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| 223 | *  | 
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| 224 | * @return static  | 
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| 225 | */  | 
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| 226 | public static function instance(DateInterval $di)  | 
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| 238 | |||
| 239 | /**  | 
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| 240 | * @param string $intervalSpec  | 
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| 241 | *  | 
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| 242 | * @return Interval  | 
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| 243 | */  | 
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| 244 | public static function createFromSpec($intervalSpec)  | 
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| 250 | |||
| 251 | ///////////////////////////////////////////////////////////////////  | 
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| 252 | ///////////////////////// GETTERS AND SETTERS /////////////////////  | 
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| 253 | ///////////////////////////////////////////////////////////////////  | 
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| 254 | |||
| 255 | /**  | 
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| 256 | * Get a part of the Interval object.  | 
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| 257 | *  | 
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| 258 | * @param string $name  | 
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| 259 | *  | 
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| 260 | * @throws InvalidArgumentException  | 
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| 261 | *  | 
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| 262 | * @return int  | 
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| 263 | */  | 
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| 264 | public function __get($name)  | 
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| 296 | |||
| 297 | /**  | 
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| 298 | * Set a part of the Interval object.  | 
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| 299 | *  | 
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| 300 | * @param string $name  | 
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| 301 | * @param int $val  | 
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| 302 | *  | 
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| 303 | * @throws InvalidArgumentException  | 
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| 304 | */  | 
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| 305 | public function __set($name, $val)  | 
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| 337 | |||
| 338 | /**  | 
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| 339 | * Allow setting of weeks and days to be cumulative.  | 
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| 340 | *  | 
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| 341 | * @param int $weeks Number of weeks to set  | 
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| 342 | * @param int $days Number of days to set  | 
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| 343 | *  | 
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| 344 | * @return static  | 
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| 345 | */  | 
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| 346 | public function weeksAndDays($weeks, $days)  | 
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| 352 | |||
| 353 | /**  | 
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| 354 | * Allow fluent calls on the setters... Interval::years(3)->months(5)->day().  | 
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| 355 | *  | 
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| 356 | * Note: This is done using the magic method to allow static and instance methods to  | 
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| 357 | * have the same names.  | 
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| 358 | *  | 
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| 359 | * @param string $name  | 
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| 360 | * @param array $args  | 
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| 361 | *  | 
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| 362 | * @return static  | 
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| 363 | */  | 
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| 364 | public function __call($name, $args)  | 
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| 408 | |||
| 409 | /**  | 
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| 410 | * Get the current interval in a human readable format in the current locale.  | 
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| 411 | *  | 
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| 412 | * @return string  | 
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| 413 | */  | 
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| 414 | public function forHumans()  | 
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| 435 | |||
| 436 | /**  | 
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| 437 | * Format the instance as a string using the forHumans() function.  | 
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| 438 | *  | 
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| 439 | * @return string  | 
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| 440 | */  | 
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| 441 | public function __toString()  | 
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| 445 | |||
| 446 | /**  | 
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| 447 | * Add the passed interval to the current instance.  | 
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| 448 | *  | 
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| 449 | * @param DateInterval $interval  | 
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| 450 | *  | 
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| 451 | * @return static  | 
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| 452 | */  | 
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| 453 | public function add(DateInterval $interval)  | 
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| 470 | }  | 
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| 471 |