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 ServiceFactory 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 ServiceFactory, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 19 | class ServiceFactory  | 
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| 20 | { | 
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| 21 | /**  | 
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| 22 | * Creates and initializes service instance from a given configuration.  | 
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| 23 | *  | 
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| 24 | * @param $config configuration of the service  | 
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| 25 | *  | 
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| 26 | * @return object the initialized service instance  | 
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| 27 | */  | 
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| 28 | public static function createService(array $config)  | 
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| 40 | |||
| 41 | /**  | 
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| 42 | * Builds an arbitrary service/object instance from a config-obect.  | 
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| 43 | *  | 
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| 44 | * @static  | 
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| 45 | *  | 
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| 46 | * @param object $config configuration object to build a service instance from.  | 
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| 47 | * @param array $arguments arguments for the service constructor  | 
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| 48 | * @param string $defaultClass class to create instance for if none is set in config  | 
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| 49 | *  | 
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| 50 | * @return object build and modified srvice instance  | 
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| 51 | */  | 
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| 52 | public static function doBuild($config, $arguments, $defaultClass = false)  | 
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| 72 | |||
| 73 | /**  | 
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| 74 | * Utility function to build an object instance for given class with given constructor-arguments.  | 
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| 75 | *  | 
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| 76 | * @see GenericBuilder  | 
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| 77 | * @static  | 
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| 78 | *  | 
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| 79 | * @param string $className name of class to build instance for.  | 
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| 80 | * @param array $arguments arguments for the constructor  | 
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| 81 | *  | 
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| 82 | * @return object build and modified srvice instance  | 
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| 83 | */  | 
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| 84 | public static function build($className, $arguments)  | 
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| 88 | |||
| 89 | /**  | 
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| 90 | * Builds single argument (to call a method with later) from a config-obect.  | 
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| 91 | *  | 
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| 92 | * @param object $config configuration object to create argument from.  | 
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| 93 | *  | 
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| 94 | * @return mixed build argument  | 
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| 95 | */  | 
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| 96 | protected static function buildArg($config)  | 
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| 125 | |||
| 126 | /**  | 
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| 127 | * Builds and modifies an arbitrary service/object instance from a config-obect.  | 
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| 128 | *  | 
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| 129 | * @see XMLContext::doBuild  | 
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| 130 | * @see PEIP\Factory\ServiceFactory::modifyService  | 
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| 131 | * @implements \PEIP\INF\Context\Context  | 
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| 132 | *  | 
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| 133 | * @param object $config configuration array to build a service instance from.  | 
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| 134 | * @param array $arguments arguments for the service constructor  | 
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| 135 | * @param string $defaultClass class to create instance for if none is set in config  | 
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| 136 | *  | 
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| 137 | * @return object build and modified srvice instance  | 
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| 138 | */  | 
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| 139 | public static function buildAndModify(array $config, $arguments, $defaultClass = '')  | 
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| 164 | |||
| 165 | /**  | 
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| 166 | * Modifies a service instance from configuration.  | 
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| 167 | * - Sets properties on the instance.  | 
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| 168 | * -- Calls a public setter method if exists.  | 
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| 169 | * -- Else sets a public property if exists.  | 
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| 170 | * - Calls methods on the instance.  | 
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| 171 | * - Registers listeners to events on the instance.  | 
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| 172 | *  | 
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| 173 | * @param object $service the service instance to modify  | 
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| 174 | * @param object $config configuration to get the modification instructions from.  | 
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| 175 | *  | 
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| 176 | * @return object the modificated service  | 
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| 177 | */  | 
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| 178 | protected function modifyService($service, $config)  | 
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| 221 | }  | 
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| 222 | 
If you define a variable conditionally, it can happen that it is not defined for all execution paths.
Let’s take a look at an example:
In the above example, the variable $x is defined if you pass “foo” or “bar” as argument for $a. However, since the switch statement has no default case statement, if you pass any other value, the variable $x would be undefined.
Available Fixes
Check for existence of the variable explicitly:
Define a default value for the variable:
Add a value for the missing path: