[英]How access outside variables from within class?
I have two class called them class A and B. I created the 'A' class. 我有两个类叫做A类和B类。我创建了'A'类。 And in this i create a 'B' class.
在这个我创建一个'B'类。 How can i access the 'A' class variable from 'B' class?
如何从'B'类访问'A'类变量?
class A
{
var letter;
var writers;
function __construct()
{
$this-letter = 'SOMETHING';
$this->writers = new B;
}
}
class B extends Writers
{
function __construct()
{
parent::__construct();
echo $letter; //This is where i want to acces outside variable (CLASS 'A')
}
}
I hope i was clear. 我希望我很清楚。 I'm just rookie on OOP-ing.
我只是OOP的新秀。 Please help me.
请帮我。
You can't, because $letter
in A is was not declared public and B doesn't extend A. 你不能,因为A中的
$letter
未被公开 ,B不会扩展A.
If you don't want to expose A's data (one of the important OOP principles), you should use encapsulation. 如果您不想公开A的数据(重要的OOP原则之一),则应使用封装。 Create a getter in the A class
在A类中创建一个getter
public function getLetter()
{
return $this->letter;
}
And then in B's construct method, create an instance of A and use said getter 然后在B的构造方法中,创建一个A的实例并使用所述的getter
$a = new A();
$letter = $a->getLetter();
In case you really need to use this structure, I guess you could do something like this: 如果你真的需要使用这个结构,我猜你可以这样做:
class A
{
var letter;
var writers;
function __construct()
{
$this-letter = 'SOMETHING';
$this->writers = new B($this);
}
}
class B extends Writers
{
var $a;
function __construct(A $a)
{
parent::__construct();
$this->a = $a;
echo $this->a->letter;
}
}
This way, B
would hold a reference to the A
object it was created by. 这样,
B
将保存对其创建的A
对象的引用。 However, I rather recommend you to change your class topology, if possible. 但是,如果可能,我建议您更改类拓扑。
Your B class needs to somehow have a reference to an A object. 你的B类需要以某种方式引用A对象。 You could simply add to B :
你可以简单地添加到B:
class B extends Writers
{
private $a;
function __construct()
{
parent::__construct();
echo $letter; //This is where i want to acces outside variable (CLASS 'A')
}
public function A($a)
{
$this->a = $a;
}
}
Next, simply have your A object give a reference to itself to its B object. 接下来,让您的A对象为其B对象提供对自身的引用。
class A
{
var letter;
var writers;
function __construct()
{
$this-letter = 'SOMETHING';
$this->writers = new B;
$this->writers->A($this);
}
}
The alternative would be static method. 替代方案是静态方法。
It's hard to tell exactly what you want, but as I interpreted it: 很难确切地说出你想要什么,但正如我解释的那样:
class A extends Writers
{
var letter;
var writers;
function __construct()
{
$this-letter = 'SOMETHING';
$this->writers = new B;
}
}
class B extends A
{
function __construct()
{
parent::__construct();
echo $this->letter; //This is where i want to acces outside variable (CLASS 'A')
}
}
You can use static variable. 您可以使用静态变量。 like this:
像这样:
class A
{
static $letter;
function __construct()
{
self::$letter = 'SOMETHING';
}
}
$objA = new A();
class B
{
function __construct()
{
$letter = A::$letter;
echo $letter; //print SOMETHING
}
}
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