private function __construct() not working when class called on another page

Question

im using the following type of class...

class datas{


    protected $req ;
    protected $db ;


    private function __construct()
    {
        $this->db = new Database('localhost', 'user', 'pass', 'db');
        $this->db->connect(); 
    }

    public function prnt()
    {
       echo "afafa6e5f1ga56d18a1ge";
    }
}

when i try and access the class like

$y = new datas();
$y->prnt();

Call to protected data::__construct() from invalid context

when i turn it to public, it works. is there any way to make the constructor private and still have the method of call like i have. and i was thinking which one is more secure .

any insight is appreciated guys.

A class with private or protected cannot be instantiated. See http://stackoverflow.com/questions/1997721/fatal-error-call-to-private-myobject-construct-from-invalid-context. — bnlucas, Jul 26 '13 at 17:21
note there is a discrepancy between the class name and visibility in the class and in the error message (data vs datas, protected vs private). In any case, a non-public ctor obeys the same rules as any other non-public method in terms of where it can be called. — Gordon, Jul 26 '13 at 17:21

score 2 · Answer 1 · answered Jul 26 '13 at 17:19

2

Your constructor should be public because it's being called outside of the class context.

PHP may hide that for you, with new, but that's still what's happening.

answered Jul 26 '13 at 17:19

adpalumbo

3,031
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is there a way to call it inside the class context ? – mega-crazy Jul 26 '13 at 17:20
You could create a static public member function on the class, and have it `return new datas();`. Instead of using `new` to create a new instance outside the class, you'd use `$x = datas::MyStaticFunction();` – adpalumbo Jul 26 '13 at 17:27
yeah, but why? I mean, if the OP can change the class, then s/he can just as well change the ctor back to public. – Gordon Jul 26 '13 at 17:38
I'm not here to ask why; I'm just answering their questions. But this would just be a Factory pattern. There could be any number of reasons to do this, and some of them are actually legitimate. In a real world example, maybe datas is an abstract base class and `datas::MyStaticFunction()` will return a different subclass of datas depending on which database the user configured for the app. – adpalumbo Jul 26 '13 at 17:43

score -1 · Answer 2 · answered Jul 26 '13 at 17:18

-1

$y = new data();

should be

$y = new datas();

answered Jul 26 '13 at 17:18

Maximus2012

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yea ok...that was just a typo..thanks... – mega-crazy Jul 26 '13 at 17:20
could the issue be in Database class constructor ? if I comment out the DB connection part (since I don't have code for that class), your code seems to be working. – Maximus2012 Jul 26 '13 at 17:23
nah changed it....it should have been private function __construct() – mega-crazy Jul 26 '13 at 17:25
why do you want a private constructor ? – Maximus2012 Jul 26 '13 at 17:26
1

given that the ctor holds a Database class my assumption is that this is an attempt at creating a [Singleton](http://stackoverflow.com/questions/4595964/who-needs-singletons/4596323#4596323). – Gordon Jul 26 '13 at 17:39
that makes sense. I think this answer also addresses something similar: http://stackoverflow.com/questions/26079/in-a-php5-class-when-does-a-private-constructor-get-called – Maximus2012 Jul 26 '13 at 17:40

private function __construct() not working when class called on another page

2 Answers2