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 Container 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 Container, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 31 | class Container extends Component implements ContainerInterface, FactoryInterface, ResolverInterface  | 
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| 32 | { | 
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| 33 | /**  | 
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| 34 | * IoC bindings.  | 
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| 35 | *  | 
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| 36 | * @invisible  | 
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| 37 | * @var array  | 
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| 38 | */  | 
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| 39 | protected $bindings = [];  | 
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| 40 | |||
| 41 | /**  | 
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| 42 | * Registered injectors.  | 
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| 43 | *  | 
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| 44 | * @invisible  | 
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| 45 | * @var array  | 
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| 46 | */  | 
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| 47 | protected $injectors = [];  | 
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| 48 | |||
| 49 | /**  | 
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| 50 |      * {@inheritdoc} | 
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| 51 | */  | 
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| 52 | public function has($alias)  | 
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| 56 | |||
| 57 | /**  | 
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| 58 |      * {@inheritdoc} | 
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| 59 | *  | 
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| 60 | * Context parameter will be passed to class injectors, which makes possible to use this method  | 
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| 61 | * as:  | 
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| 62 | * $this->container->get(DatabaseInterface::class, 'default');  | 
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| 63 | *  | 
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| 64 | * @param string|null $context Call context.  | 
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| 65 | */  | 
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| 66 | public function get($alias, $context = null)  | 
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| 71 | |||
| 72 | /**  | 
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| 73 |      * {@inheritdoc} | 
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| 74 | *  | 
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| 75 | * @param string|null $context Related to parameter caused injection if any.  | 
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| 76 | */  | 
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| 77 | public function make($class, $parameters = [], $context = null)  | 
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| 136 | |||
| 137 | /**  | 
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| 138 |      * {@inheritdoc} | 
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| 139 | */  | 
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| 140 | public function resolveArguments(ContextFunction $reflection, array $parameters = [])  | 
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| 202 | |||
| 203 | /**  | 
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| 204 |      * {@inheritdoc} | 
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| 205 | *  | 
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| 206 | * @return $this  | 
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| 207 | */  | 
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| 208 | View Code Duplication | public function bind($alias, $resolver)  | 
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| 220 | |||
| 221 | /**  | 
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| 222 |      * {@inheritdoc} | 
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| 223 | *  | 
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| 224 | * @return $this  | 
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| 225 | */  | 
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| 226 | View Code Duplication | public function bindSingleton($alias, $resolver)  | 
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| 238 | |||
| 239 | /**  | 
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| 240 |      * {@inheritdoc} | 
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| 241 | *  | 
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| 242 | * @return $this  | 
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| 243 | */  | 
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| 244 | public function bindInjector($class, $injector)  | 
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| 250 | |||
| 251 | /**  | 
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| 252 |      * {@inheritdoc} | 
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| 253 | */  | 
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| 254 | public function replace($alias, $resolver)  | 
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| 265 | |||
| 266 | /**  | 
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| 267 |      * {@inheritdoc} | 
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| 268 | */  | 
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| 269 | public function restore($replacePayload)  | 
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| 280 | |||
| 281 | /**  | 
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| 282 |      * {@inheritdoc} | 
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| 283 | */  | 
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| 284 | public function hasInstance($alias)  | 
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| 297 | |||
| 298 | /**  | 
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| 299 |      * {@inheritdoc} | 
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| 300 | */  | 
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| 301 | public function removeBinding($alias)  | 
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| 305 | |||
| 306 | /**  | 
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| 307 | * Every declared Container binding. Must not be used in production code due container format is  | 
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| 308 | * vary.  | 
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| 309 | *  | 
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| 310 | * @return array  | 
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| 311 | */  | 
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| 312 | public function getBindings()  | 
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| 316 | |||
| 317 | /**  | 
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| 318 | * Every binded injector.  | 
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| 319 | *  | 
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| 320 | * @return array  | 
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| 321 | */  | 
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| 322 | public function getInjectors()  | 
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| 326 | |||
| 327 | /**  | 
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| 328 | * Automatically create class.  | 
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| 329 | *  | 
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| 330 | * @param string $class  | 
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| 331 | * @param array $parameters  | 
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| 332 | * @param string $context  | 
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| 333 | * @return object  | 
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| 334 | * @throws AutowireException  | 
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| 335 | */  | 
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| 336 | protected function autowire($class, array $parameters, $context)  | 
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| 347 | |||
| 348 | /**  | 
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| 349 | * Check if given class has associated injector.  | 
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| 350 | *  | 
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| 351 | * @todo replace with Context on demand  | 
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| 352 | * @param \ReflectionClass $reflection  | 
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| 353 | * @return bool  | 
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| 354 | */  | 
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| 355 | protected function hasInjector(\ReflectionClass $reflection)  | 
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| 363 | |||
| 364 | /**  | 
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| 365 | * Get injector associated with given class.  | 
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| 366 | *  | 
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| 367 | * @todo replace with Context on demand  | 
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| 368 | * @param \ReflectionClass $reflection  | 
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| 369 | * @return InjectorInterface  | 
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| 370 | */  | 
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| 371 | protected function getInjector(\ReflectionClass $reflection)  | 
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| 379 | |||
| 380 | /**  | 
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| 381 | * Create instance of desired class.  | 
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| 382 | *  | 
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| 383 | * @param string $class  | 
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| 384 | * @param array $parameters Constructor parameters.  | 
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| 385 | * @param string|null $context  | 
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| 386 | * @param \ReflectionClass $reflection Instance of reflection associated with class,  | 
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| 387 | * reference.  | 
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| 388 | * @return object  | 
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| 389 | * @throws ContainerException  | 
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| 390 | */  | 
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| 391 | private function createInstance(  | 
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| 438 | |||
| 439 | |||
| 440 | /**  | 
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| 441 | * Make sure instance conditions are met  | 
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| 442 | *  | 
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| 443 | * @param object $instance  | 
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| 444 | * @param \ReflectionClass $reflector  | 
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| 445 | * @param array $parameters  | 
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| 446 | * @return object  | 
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| 447 | */  | 
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| 448 | private function registerInstance($instance, \ReflectionClass $reflector, array $parameters)  | 
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| 464 | }  | 
            
Unless you are absolutely sure that the expression can never be null because of other conditions, we strongly recommend to add an additional type check to your code: