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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| 18 | abstract class AbstractQuantity implements QuantityInterface |
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| 19 | { |
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| 20 | /** |
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| 21 | * @var UnitInterface |
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| 22 | */ |
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| 23 | private $unit; |
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| 24 | |||
| 25 | /** |
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| 26 | * @var float|int|string |
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| 27 | */ |
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| 28 | private $quantity; |
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| 29 | |||
| 30 | /** |
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| 31 | * @var UnitInterface $unit |
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| 32 | * @var float|int|string $quantity |
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| 33 | */ |
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| 34 | 6 | private function __construct(UnitInterface $unit, $quantity) |
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| 39 | |||
| 40 | /** |
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| 41 | * Creates quantity with same unit. |
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| 42 | * Optimized to return this if same quantity. |
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| 43 | * @var float|int|string $quantity |
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| 44 | */ |
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| 45 | 3 | final protected function create($quantity) |
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| 49 | |||
| 50 | /** |
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| 51 | * {@inheritdoc} |
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| 52 | */ |
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| 53 | 2 | private function getCalculator() |
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| 57 | |||
| 58 | /** |
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| 59 | * {@inheritdoc} |
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| 60 | */ |
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| 61 | 2 | final public function getQuantity() |
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| 65 | |||
| 66 | /** |
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| 67 | * {@inheritdoc} |
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| 68 | */ |
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| 69 | 1 | final public function getUnit() |
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| 73 | |||
| 74 | /** |
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| 75 | * {@inheritdoc} |
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| 76 | */ |
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| 77 | 2 | final public function compare(QuantityInterface $other) |
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| 83 | |||
| 84 | /** |
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| 85 | * {@inheritdoc} |
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| 86 | */ |
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| 87 | 1 | final public function equals(QuantityInterface $other) |
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| 91 | |||
| 92 | /** |
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| 93 | * {@inheritdoc} |
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| 94 | */ |
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| 95 | 1 | final public function isConvertible(UnitInterface $unit) |
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| 99 | |||
| 100 | /** |
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| 101 | * {@inheritdoc} |
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| 102 | */ |
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| 103 | 3 | final public function convert(UnitInterface $unit) |
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| 109 | |||
| 110 | /** |
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| 111 | * {@inheritdoc} |
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| 112 | */ |
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| 113 | View Code Duplication | final public function add(QuantityInterface $addend) |
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| 120 | |||
| 121 | /** |
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| 122 | * {@inheritdoc} |
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| 123 | */ |
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| 124 | View Code Duplication | final public function subtract(QuantityInterface $subtrahend) |
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| 131 | |||
| 132 | /** |
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| 133 | * {@inheritdoc} |
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| 134 | */ |
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| 135 | final public function multiply($multiplier) |
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| 141 | |||
| 142 | /** |
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| 143 | * {@inheritdoc} |
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| 144 | */ |
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| 145 | final public function divide($divisor) |
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| 151 | |||
| 152 | /** |
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| 153 | * {@inheritdoc} |
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| 154 | */ |
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| 155 | final public function ceil() |
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| 161 | |||
| 162 | /** |
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| 163 | * {@inheritdoc} |
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| 164 | */ |
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| 165 | final public function floor() |
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| 171 | |||
| 172 | /** |
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| 173 | * {@inheritdoc} |
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| 174 | */ |
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| 175 | final public function round($roundingMode) |
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| 181 | |||
| 182 | /** |
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| 183 | * {@inheritdoc} |
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| 184 | */ |
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| 185 | final public function absolute() |
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| 191 | |||
| 192 | 6 | final public static function __callStatic($unit, $args) |
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| 196 | |||
| 197 | /** |
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| 198 | * Returns unit for given unit name. |
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| 199 | * The only function to change in child classes. |
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| 200 | * XXX Should be defined as abstract but `abstract static` is not supported in PHP5. |
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| 201 | * @param string $name |
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| 202 | * @return UnitInterface |
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| 203 | * @throws InvalidConfigException |
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| 204 | */ |
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| 205 | protected static function findUnit($unit) |
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| 209 | } |
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| 210 |
If you access a property on an interface, you most likely code against a concrete implementation of the interface.
Available Fixes
Adding an additional type check:
Changing the type hint: