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 InMemoryIndex 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 InMemoryIndex, and based on these observations, apply Extract Interface, too.
1 | <?php |
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13 | class InMemoryIndex implements Index |
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14 | { |
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15 | private $files = []; |
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16 | private $fqcns = []; |
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17 | private $classes = []; |
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18 | private $interfaces = []; |
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19 | private $extends = []; |
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20 | private $implements = []; |
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21 | private $functions = []; |
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22 | |||
23 | /** @var Index $coreIndex */ |
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24 | private static $coreIndex; |
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25 | |||
26 | public function getFQCNs() |
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30 | |||
31 | public function getImplements() { |
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37 | |||
38 | public function addFile(File $file) |
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57 | |||
58 | public function findFileByPath($path) |
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65 | |||
66 | /** |
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67 | * @return FQCN |
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68 | */ |
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69 | public function findFQCNByFile($file) |
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83 | |||
84 | /** |
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85 | * @return ClassData |
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86 | */ |
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87 | View Code Duplication | public function findClassByFQCN(FQCN $fqcn) { |
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96 | |||
97 | /** |
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98 | * @return InterfaceData |
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99 | */ |
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100 | View Code Duplication | public function findInterfaceByFQCN(FQCN $fqcn) { |
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109 | |||
110 | /** |
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111 | * @return FunctionData |
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112 | */ |
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113 | public function findFunctionByName($functionName) |
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122 | |||
123 | /** |
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124 | * @return ClassData[] |
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125 | */ |
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126 | View Code Duplication | public function findClassChildren(FQCN $class) { |
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134 | |||
135 | /** |
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136 | * @return ClassData[] |
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137 | */ |
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138 | View Code Duplication | public function findInterfaceChildrenClasses(FQCN $interface) { |
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146 | |||
147 | /** |
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148 | * @return ClassData[] |
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149 | */ |
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150 | public function getClasses() |
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158 | |||
159 | /** |
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160 | * @return InterfaceData[] |
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161 | */ |
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162 | public function getInterfaces() |
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170 | |||
171 | /** |
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172 | * @return FunctionData[] |
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173 | */ |
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174 | public function getFunctions() |
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182 | |||
183 | public function addClass(ClassData $class) { |
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197 | |||
198 | public function addInterface(InterfaceData $interface) { |
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209 | |||
210 | public function addFunction(FunctionData $function) |
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214 | |||
215 | public function addFQCN(FQCN $fqcn) { |
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218 | |||
219 | protected function addExtend(ClassData $class, FQCN $parent) { |
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227 | |||
228 | protected function addImplement($class, FQCN $fqcn) { |
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236 | |||
237 | private function hasCoreIndex() |
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241 | } |
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242 |
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: