Call a class inside another class in PHP

问题:

Hey there I'm wondering how this is done as when I try the following code inside a function of a class it produces some php error which I can't catch

public $tasks;
$this->tasks = new tasks($this);
$this->tasks->test();

I don't know why the initiation of the class requires $this as a parameter either :S

thanks

class admin
{
    function validate()
    {
        if(!$_SESSION['level']==7){
            barMsg('YOU\'RE NOT ADMIN', 0);
            return FALSE;
        }else{
            **public $tasks;** // The line causing the problem
            $this->tasks = new tasks(); // Get rid of $this->
            $this->tasks->test(); // Get rid of $this->
            $this->showPanel();
        }
    }
}
class tasks
{
    function test()
    {
        echo 'test';
    }
}
$admin = new admin();
$admin->validate();

回答1:

You can't declare the public $tasks inside your class's method (function.) If you don't need to use the tasks object outside of that method, you can just do:

$tasks = new Tasks($this);
$tasks->test();

You only need to use the "$this->" when your using a variable that you want to be available throughout the class.

Your two options:

class Foo
{
    public $tasks;

    function doStuff()
    {
        $this->tasks = new Tasks();
        $this->tasks->test();
    }

    function doSomethingElse()
    {
        // you'd have to check that the method above ran and instantiated this
        // and that $this->tasks is a tasks object
        $this->tasks->blah();
    }

}

or

class Foo
{
    function doStuff()
    {
        $tasks = new tasks();
        $tasks->test();
    }
}

with your code:

class Admin
{
    function validate()
    {
        // added this so it will execute
        $_SESSION['level'] = 7;

        if (! $_SESSION['level'] == 7) {
            // barMsg('YOU\'RE NOT ADMIN', 0);
            return FALSE;
        } else {
            $tasks = new Tasks();
            $tasks->test();
            $this->showPanel();
        }
    }

    function showPanel()
    {
        // added this for test
    }
}
class Tasks
{
    function test()
    {
        echo 'test';
    }
}
$admin = new Admin();
$admin->validate();

回答2:

You're problem is with this line of code:

public $tasks;
$this->tasks = new tasks();
$this->tasks->test();
$this->showPanel();

The public keyword is used in the definition of the class, not in a method of the class. In php, you don't even need to declare the member variable in the class, you can just do $this->tasks=new tasks() and it gets added for you.