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:
| 1 | <?php  | 
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| 7 | class Form  | 
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| 8 | { | 
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| 9 | use GluesAttributes;  | 
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| 10 | |||
| 11 | /** @var array */  | 
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| 12 | protected $params;  | 
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| 13 | |||
| 14 | /** @var string */  | 
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| 15 | public $action;  | 
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| 16 | |||
| 17 | /** @var string */  | 
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| 18 | public $method;  | 
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| 19 | |||
| 20 | /** @var string */  | 
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| 21 | public $httpMethod;  | 
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| 22 | |||
| 23 | /** @var bool */  | 
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| 24 | public $files;  | 
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| 25 | |||
| 26 | /** @var string */  | 
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| 27 | public $enctype;  | 
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| 28 | |||
| 29 | /** @var Illuminate\Database\Eloquent\Model */  | 
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| 30 | public $model = null;  | 
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| 31 | |||
| 32 | /** @var bool */  | 
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| 33 | public $autocomplete;  | 
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| 34 | |||
| 35 | /** @var array */  | 
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| 36 | public $attributesList = [  | 
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| 37 | 'action', 'method', 'enctype', 'autocomplete'  | 
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| 38 | ];  | 
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| 39 | |||
| 40 | /**  | 
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| 41 | * Will be called when the form is opened.  | 
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| 42 | */  | 
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| 43 | public function setup(array $params)  | 
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| 53 | |||
| 54 | /**  | 
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| 55 | * Will be called when the form is closed.  | 
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| 56 | */  | 
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| 57 | public function delete()  | 
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| 65 | |||
| 66 | protected function setModel()  | 
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| 72 | |||
| 73 | protected function setAction()  | 
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| 79 | |||
| 80 | protected function setMethod()  | 
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| 105 | |||
| 106 | protected function setFiles()  | 
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| 113 | |||
| 114 | View Code Duplication | protected function setAutocomplete()  | 
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| 123 | }  | 
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| 124 | 
In PHP it is possible to write to properties without declaring them. For example, the following is perfectly valid PHP code:
Generally, it is a good practice to explictly declare properties to avoid accidental typos and provide IDE auto-completion: