php callback function in class

Question

for some reasons, our hosting company used PHP 5.2 and doesn't even have mysqli and PDO pre-installed.

I have no choice but to rewrite some part of my code to make it 5.2 compatible.

so, here is my question:

In PHP 5.2 Anonymous function is not supported, so i did the following test to make sure I'm changing the code correctly:

class foo{

    public function toString(){
        $arr = array("a", "b");
        $arr2 = array("c", "d");
        print_r(array_map('mapKeyValue', $arr, $arr2));
    }

    private function mapKeyValue($v, $k){
        return $k."='".$v."'";
    }
}

$foo = new foo();
echo $foo->toString();

but the above would give me :

Warning: array_map() expects parameter 1 to be a valid callback, function 'mapKeyValue' not found or invalid function name in ....
PHP Warning: array_map() expects parameter 1 to be a valid callback, function 'mapKeyValue' not found or invalid function name in ....

what is the correct way to do :

array_map('mapKeyValue', $arr, $arr2);

within a class?

PS: Is it a good enough reason to change hosting company because they use PHP 5.2?(i got a contract with about 7 month left)

"I have no choice but to rewrite some part of my code to make it 5.2 compatible." Or get a new host that isn't insecure by default. — ceejayoz
– ceejayoz, Commented Aug 29, 2012 at 13:53
Tell your host that you want PHP upgraded, sometimes they will actually do it. — No Results Found
– No Results Found, Commented Aug 29, 2012 at 13:54
they actually refused saying that : '5.2 supports other client better since it has "less strict standards" than 5.3' — tom91136
– tom91136, Commented Aug 29, 2012 at 13:56

nickb · Accepted Answer · 2012-08-29 13:53:03Z

19

Use $this and an array as the callback:

array_map( array( $this, 'mapKeyValue'), $arr, $arr2);

And, just to be sure, this is tested with PHP 5.2.17 and is confirmed working.

answered Aug 29, 2012 at 13:53

nickb

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Comments

Cosmin · Accepted Answer · 2015-06-12 07:06:01Z

4

Try using :

print_r(array_map(array($this, "mapKeyValue") , $arr, $arr2));

You need to call the function using $this.

edited Jun 12, 2015 at 7:06

answered Aug 29, 2012 at 13:59

Cosmin

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1 Comment

nickb Over a year ago

&$this will not boost performance, and in later versions of PHP call-time pass-by-reference has been removed.

TheHe · Accepted Answer · 2012-08-29 13:53:15Z

0

array_map(array($this, 'mapKeyValue'), $arr, $arr2);

answered Aug 29, 2012 at 13:53

TheHe

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Comments

Patrick Thach · Accepted Answer · 2013-08-25 08:47:55Z

0

Make sure your that callback method is public.

public function mapKeyValue($v, $k){
    return $k."='".$v."'";
}

print_r(array_map(array($this, "mapKeyValue") , $arr, $arr2));

answered Aug 25, 2013 at 8:47

Patrick Thach

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