class public variable calls compatible in PHP 7.0 and PHP 5.6

Question

In PHP 5.6:

When being inside a class we usually declare & call a public class variable like this:

class MyClass
{
    /**
     * @var int
     */
    public $myVar = 0;

    // call it in a public function:
   public function myFunction()
   {
       return $this->myVar;
   }

}

I call the function like this:

MyClass::myFunction();

In PHP 7.0 that code throws a fatal error:

Using $this when not in object context

After changing my PHP version back to 5.6 again, the error was gone.

Questions:

I have to admit that after reading the manual and changes from 5.6 to 7.0 I don't get it.

How do we declare and call public class variables in PHP 7.0?
How do we write this code to be compatible between 5.6 and 7.0?

Edit after comments:

So why then a static call on a non static method works in 5.6?

I'm rather sure you're analyzing the error incorrectly. The code you are showing is fine. I agree with the above that it is the calling of said method that is the cause. — Anees Saban, May 06 '16 at 10:04
It's not a static function, and if it was. Your variable is not static. — Anees Saban, May 06 '16 at 10:05
http://php.net/manual/en/migration70.deprecated.php - Static calls to non-static methods — Anees Saban, May 06 '16 at 10:06
I've just tested in both, php5 and php7. There is no difference in behavior. — Pinke Helga, May 06 '16 at 10:18
It doesn't work as you want in 5.6, but you're probably suppressing the messages in your 5.6... 7 has made the messages stricter [Demo](https://3v4l.org/cvgP2) — Mark Baker, May 06 '16 at 10:29
I've setup a test case, where this fatal error occurs. This is when you already are in a $this context. — Pinke Helga, May 06 '16 at 10:39
@MarkBaker Try out my example below. It throws a fatal error in 7 but not even a warning in 5. — Pinke Helga, May 06 '16 at 10:49
Not even a warning?!? 5.6 gives `Deprecated: Non-static method MyClass::myFunction() should not be called statically, assuming $this from incompatible context in /in/T4Qbm on line 26 2` and 5.5 gives `Strict Standards: Non-static method MyClass::myFunction() should not be called statically, assuming $this from incompatible context in /in/T4Qbm on line 26 2` [Demo](https://3v4l.org/T4Qbm) — Mark Baker, May 06 '16 at 10:54
@MarkBaker Check, in my CLI version error reporting had become disabled for some reason, probably due to an update. — Pinke Helga, May 06 '16 at 11:12

score 5 · Accepted Answer · answered May 06 '16 at 10:02

In I'm loading maybe func() like this:

 obj::func();  // Wrong, it is not static method

but can also be

$obj = new Obj();  // correct
$obj->func();

You can not invoke method this way because it is not static method.

obj::func();

You should instead use:

obj->func();

If however you have created a static method something like:

static $foo; // your top variable set as static

public static function foo() {
    return self::$foo;
}

then you can use this:

obj::func();

Pinke Helga · Answer 2 · 2016-05-06T10:41:04.647

The behavior you describe can be found in the following example:

<?php

class MyClass
{
  /**
   * @var int
   */
  public $myVar = 1;

  // call it in a public function:
  public function myFunction()
  {
    return $this->myVar;
  }    
}

class MyClass2
{
  /**
   * @var int
   */
  public $myVar = 2;

  public function test()
  {
    echo MyClass::myFunction();
    // outputs: 2
  }
}


$obj = new MyClass2();
$obj->test();
?>

In PHP 5 you can call a public method of other classes, when you are inside an instance. It will work as it was a member of the class in the current $this context. PHP 7 is more stict. You can extend classes or import traits into classes in different inheritance lines. There is no need to steel other classes' methods. You can still use the Classname::method() or parent::method() syntax to call ancestor's methods.

score 0 · Answer 3 · answered May 06 '16 at 10:15

You accomplish the same by instantiating object of that class and then call that class's method.

class MyClass
{
    /**
     * @var int
     */
    public $myVar = 0;

    // call it in a public function:
   public function myFunction()
   {
       return $this->myVar;
   }

}
$obj = new Myclass();
$result = $obj->myFunction();
print $result;

class public variable calls compatible in PHP 7.0 and PHP 5.6

3 Answers3