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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| 9 | trait HasAttributesTrait  | 
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| 10 | { | 
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| 11 | protected $_attribs;  | 
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| 12 | |||
| 13 | /**  | 
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| 14 | * @return mixed  | 
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| 15 | */  | 
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| 16 | public function getId()  | 
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| 20 | |||
| 21 | /**  | 
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| 22 | * @param $id  | 
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| 23 | * @return $this  | 
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| 24 | */  | 
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| 25 | public function setId($id)  | 
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| 31 | |||
| 32 | /**  | 
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| 33 | * @return null  | 
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| 34 | */  | 
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| 35 | 6 | public function getName()  | 
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| 39 | |||
| 40 | |||
| 41 | /**  | 
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| 42 | * @param $name  | 
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| 43 | * @return $this  | 
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| 44 | */  | 
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| 45 | 5 | public function setName($name)  | 
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| 51 | |||
| 52 | /**  | 
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| 53 | * @return string  | 
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| 54 | */  | 
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| 55 | 5 | public function getLabel()  | 
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| 59 | |||
| 60 | /**  | 
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| 61 | * @param $label  | 
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| 62 | * @return $this  | 
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| 63 | */  | 
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| 64 | 5 | public function setLabel($label)  | 
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| 70 | |||
| 71 | /**  | 
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| 72 | * @param string $requester  | 
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| 73 | * @return null  | 
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| 74 | */  | 
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| 75 | 4 | public function getValue($requester = 'abstract')  | 
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| 79 | |||
| 80 | /**  | 
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| 81 | * @return bool  | 
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| 82 | */  | 
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| 83 | 5 | public function hasValue()  | 
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| 87 | |||
| 88 | /**  | 
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| 89 | * @param $value  | 
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| 90 | * @return static|self  | 
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| 91 | */  | 
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| 92 | 4 | public function setValue($value)  | 
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| 98 | |||
| 99 | /**  | 
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| 100 | * @return $this  | 
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| 101 | */  | 
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| 102 | 3 | View Code Duplication | public function addClass()  | 
            
| 113 | |||
| 114 | /**  | 
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| 115 | * @return $this  | 
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| 116 | */  | 
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| 117 | View Code Duplication | public function removeClass()  | 
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| 133 | |||
| 134 | /**  | 
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| 135 | * @param $key  | 
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| 136 | * @param $value  | 
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| 137 | * @return static  | 
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| 138 | */  | 
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| 139 | 6 | public function setAttrib($key, $value)  | 
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| 146 | |||
| 147 | /**  | 
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| 148 | * @param string $key  | 
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| 149 | * @return null  | 
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| 150 | */  | 
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| 151 | 8 | View Code Duplication | public function getAttrib($key)  | 
            
| 160 | |||
| 161 | /**  | 
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| 162 | * @param string $key  | 
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| 163 | * @return bool  | 
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| 164 | */  | 
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| 165 | public function delAttrib($key)  | 
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| 172 | |||
| 173 | /**  | 
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| 174 | * @return mixed  | 
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| 175 | */  | 
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| 176 | 3 | public function getAttribs()  | 
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| 180 | |||
| 181 | /**  | 
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| 182 | * @param array $attribs  | 
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| 183 | * @return static  | 
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| 184 | */  | 
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| 185 | public function setAttribs(array $attribs)  | 
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| 191 | |||
| 192 | /**  | 
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| 193 | * @return static  | 
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| 194 | */  | 
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| 195 | public function clearAttribs()  | 
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| 201 | |||
| 202 | /**  | 
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| 203 | * @param array $attribs  | 
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| 204 | * @return static  | 
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| 205 | */  | 
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| 206 | 3 | public function addAttribs(array $attribs)  | 
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| 214 | |||
| 215 | /**  | 
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| 216 | * @param $key  | 
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| 217 | * @return bool  | 
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| 218 | */  | 
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| 219 | View Code Duplication | public function removeAttrib($key)  | 
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| 229 | }  | 
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| 230 | 
This check looks from parameters that have been defined for a function or method, but which are not used in the method body.