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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| 10 | class ValueProxy |
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| 11 | { |
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| 12 | /** コールバック関数 */ |
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| 13 | private $callback; |
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| 14 | /** コンテキスト */ |
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| 15 | private $context; |
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| 16 | /** キャッシュするかどうか */ |
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| 17 | private $cached; |
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| 18 | /** コールバックの実行結果 */ |
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| 19 | private $value; |
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| 20 | |||
| 21 | /** |
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| 22 | * コンストラクタ |
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| 23 | * @param callable $callback コールバック関数 |
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| 24 | * @param array $context コンテキスト |
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| 25 | * @param boolean $cached キャッシュするかどうか |
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| 26 | * @return void |
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| 27 | */ |
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| 28 | public function __construct($callback, $context = [], $cached = true) |
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| 29 | { |
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| 30 | $this->callback = $callback; |
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| 31 | $this->cached = $cached; |
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| 32 | $this->context = $context; |
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| 33 | } |
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| 34 | |||
| 35 | /** |
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| 36 | * 評価する |
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| 37 | * @return mixed 実行結果 |
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| 38 | */ |
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| 39 | public function fetch() |
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| 40 | { |
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| 41 | if ($this->cached && isset($this->value)) { |
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| 42 | return $this->value; |
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| 43 | } |
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| 44 | $args = $this->context; |
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| 45 | // useで引数を指定した場合、call_user_func_arrayの$argsと |
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| 46 | // 引数の数が合わなくなり警告が出るが問題なく実行出来る |
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| 47 | $result = @call_user_func_array($this->callback, $args); |
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| 48 | if ($this->cached) { |
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| 49 | $this->value = $result; |
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| 50 | } |
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| 51 | |||
| 52 | return $result; |
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| 53 | } |
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| 54 | } |
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| 55 |