# 第七課 面向對象 > 定義對象 ``` <pre class="calibre14">``` class <span class="token1">Book</span><span class="token2">{</span> const PI<span class="token">=</span><span class="token3">3.14</span><span class="token2">;</span><span class="token6">//常量</span> private $name<span class="token2">;</span><span class="token6">//私有不可繼承</span> public $sex<span class="token2">;</span> <span class="token5">function</span> <span class="token1">__construct</span><span class="token2">(</span>$name<span class="token2">,</span>$sex<span class="token2">)</span><span class="token2">{</span><span class="token6">//構造方法</span> $this<span class="token">-</span><span class="token">></span><span class="token1">name</span><span class="token2">(</span>$name<span class="token2">)</span><span class="token2">;</span> <span class="token2">}</span> <span class="token5">function</span> <span class="token1">__destruct</span><span class="token2">(</span><span class="token2">)</span><span class="token2">{</span> echo <span class="token4">"析構方法."</span><span class="token2">;</span> <span class="token2">}</span> public <span class="token5">function</span> <span class="token1">name</span><span class="token2">(</span>$name<span class="token2">)</span><span class="token2">{</span><span class="token6">//設置</span> $this<span class="token">-</span><span class="token">></span>name <span class="token">=</span> $name<span class="token2">;</span> <span class="token5">return</span> $this<span class="token">-</span><span class="token">></span>name<span class="token2">;</span> <span class="token2">}</span> <span class="token2">}</span> ``` ``` 繼承 ``` <pre class="calibre14">``` class <span class="token1">A</span> extends <span class="token1">B</span><span class="token2">{</span> <span class="token2">}</span> ``` ``` parent 調用父類 self 調用當前類靜態方法和變量,在靜態方法中,必須用self::調用本類中方法 public 公共的 private 私有,本類中調用,子類不可繼承 protected受保護,子類可調用 命名空間 namespace logoove\\qq; 命名空間內使用調用類 use logoove\\qq\\類名; 命名空間內如果調用未使用空間命名類 require\_once加載 類名前加\\ 比如 new \\phpExcel()