CODEWITHSUNDEEP
phpclassmethodsstaticsingleton
anovsiradj
anovsiradj

Reputation: 43

PHP, error set static variable for class instance inside class

I'm trying call class method inside another class.

<?php
class A {
    public static $instant = null;
    public static $myvariable = false;

    private function __construct() {}

    public static function initial() {
        if (static::$instant === null) {
            $self = __CLASS__;
            static::$instant = new $self;
        }
        return static::$instant; // A instance
    }
}

class B {
    private $a;

    function __construct($a_instance) {
        $this->a = $a_instance;
    }

    public function b_handle() {
        // should be:
        $this->a::$myvariable = true;
        // but:
        // Parse error: syntax error, unexpected '::' (T_PAAMAYIM_NEKUDOTAYIM)

        // try with:
        // $this->a->myvariable = true;
        // but:
        // Strict Standards: Accessing static property A::$myvariable as non static
    }
}

// in file.php
$b = new B(A::initial());
$b->b_handle();

var_dump(A::$myvariable);

for now, my alternative is:

<?php
class A {
    public function set_static($var,$val) {
        static::$$var = $val;
    }
}

so:

$this->a->set_static('myvariable',true);

what should I do ? what is happen ? am I wrong ?

why I cannot set myvariable as static variable direcly from B class ?

sorry for bad english.

Upvotes: 1

Views: 1291

Answers (2)

u_mulder
u_mulder

Reputation: 54841

Refer to the manual: http://php.net/manual/en/language.oop5.static.php

A property declared as static cannot be accessed with an instantiated class object (though a static method can).

So, you cannot in anyway set static property from class instance.

As an option you can add some setter, which set your static variable:

public function setMyVar($value) {
    static::$myvariable = $value;
}

$this->a->setMyVar(true);

Upvotes: 2

Rajdeep Paul
Rajdeep Paul

Reputation: 16963

Your call,

$this->a::$myvariable = true;

The PHP manual says,

Declaring class properties or methods as static makes them accessible without needing an instantiation of the class. A property declared as static can not be accessed with an instantiated class object (though a static method can).

This is why you are unable to assign static property through an object.

Simply do this:

A::$myvariable = true;

Here's the reference:

Upvotes: 1

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