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php基礎(chǔ)知識(shí):類與對(duì)象(5) static

更新時(shí)間：2006年12月13日 00:00:00 作者：

Declaring class members or methods as static makes them accessible without needing an instantiation of the class. A member declared as static can not be accessed with an instantiated class object (though a static method can).
聲明靜態(tài)的類變量和方法可以不需要實(shí)例化類對(duì)象的情況下對(duì)他們進(jìn)行調(diào)用。靜態(tài)類不能被類對(duì)象調(diào)用。(類的靜態(tài)方法可以)。//注意看第一個(gè)例子,在一個(gè)非靜態(tài)的方法中調(diào)用了靜態(tài)的變量。唯一的不同是用了self。難道用了self就可以????不知道???需要一個(gè)試驗(yàn)。

The static declaration must be after the visibility declaration. For compatibility with PHP4, if no visibility declaration is used, then the member or method will be treated as if it was declared as public.
靜態(tài)聲明必須必須是顯式的聲明。為了兼容PHP4,如果沒有顯式聲明的對(duì)象或者方法,被當(dāng)作聲明為public。

Because static methods are callable without an instance of the object created, the pseudo variable $this is not available inside the method declared as static.
因?yàn)殪o態(tài)方法不需要實(shí)例化類對(duì)象來調(diào)用,所以偽變量$this在靜態(tài)方法中也是不可用的。

In fact static method calls are resolved at compile time. When using an explicit class name the method is already identified completely and no inheritance rules apply. If the call is done by self then self is translated to the current class, that is the class the code belongs to. Here also no inheritance rules apply.
實(shí)際上,靜態(tài)的方法調(diào)用在編譯時(shí)已經(jīng)確定了。(這段我不會(huì)翻譯。???不明白???)
求了很久求來的翻譯如下:
------------------------------------------------
實(shí)際上，靜態(tài)方法的調(diào)用在編譯時(shí)解決。當(dāng)使用一個(gè)明確的類名時(shí)，方法已經(jīng)被完全識(shí)別而不需要應(yīng)用繼承規(guī)則。如果由自身調(diào)用，那么自身被解析成當(dāng)前的類，也就是代碼所屬的類。這里也沒有應(yīng)用繼承規(guī)則。
但是一個(gè)新的問題:
這里不一定有繼承產(chǎn)生，為什么會(huì)提到繼承規(guī)則?(???不明白????)

Static properties cannot be accessed through the object using the arrow operator ->. Calling non-static methods statically generates an E_STRICT level warning.
靜態(tài)成員不能被類的對(duì)象通過箭頭符號(hào)->來調(diào)用。靜態(tài)的調(diào)用一個(gè)非靜態(tài)方法會(huì)導(dǎo)致一個(gè)E_STRICT級(jí)別的警告。

靜態(tài)成員例:

復(fù)制代碼代碼如下:

class Foo  
{  
   public static $my_static = 'foo';   
   public function staticValue() {  
       return self::$my_static;//注意這里!!!!  
       //return $my_static;//這樣寫會(huì)不會(huì)出錯(cuò)。需要試驗(yàn)  
   }  
}  

class Bar extends Foo  
{  
   public function fooStatic() {  
       return parent::$my_static;//注意這里!!!!  
   }  
}  
print Foo::$my_static . " n";  
$foo = new Foo();  
print $foo->staticValue() . " n";  
print $foo->my_static . " n";      // 未定義的"Property" my_static   
// $foo::my_static is not possible  
print Bar::$my_static . " n";  
$bar = new Bar();  
print $bar->fooStatic() . " n";  

靜態(tài)方法例:  
class Foo {  
   public static function aStaticMethod() {  
       // ...  
   }  
}  
Foo::aStaticMethod(); 