公共靜態變量值

Question

我想聲明一個公共靜態變量是陣列的陣列：

class Foo{ 
public static $contexts = array(
    'a' => array(
     'aa'    => something('aa'), 
     'bb'    => something('bb'), 
    ), 

    'b' => array(
     'aa'    => something('aa'), 
     'bb'    => something('bb'), 
    ), 

); 

// methods here 

} 

function something($s){ 
    return ... 
} 

但我得到一個錯誤：

Parse error: parse error, expecting `')'' in ...

Answer 1

你不能使用表達式當聲明類屬性時。即您不能在這裏撥打something()，您只能使用靜態值。您必須在某些時候以不同的代碼設置這些值。

Like any other PHP static variable, static properties may only be initialized using a literal or constant; expressions are not allowed. So while you may initialize a static property to an integer or array (for instance), you may not initialize it to another variable, to a function return value, or to an object.

http://www.php.net/manual/en/language.oop5.static.php

例如：

class Foo { 
    public static $bar = null; 

    public static function init() { 
     self::$bar = array(...); 
    } 
} 

Foo::init(); 

或做它__construct，如果你打算將類實例。