Two Questions: 1) Calling Parent Function 2) Static Function

[sfc]

Question 1) Is the only and proper way to call a parent function "parent::function()"?  Are there other/better ways from within a child function?

 

Question 2) What are the deciding factors for when to make a function or attribute static?  How do you make that decision?  Assuming 5.3...

 

Thanks.

[JonnoTheDev]

Question 1) Is the only and proper way to call a parent function "parent::function()"?  Are there other/better ways from within a child function?

No. See below.

<?php
class foo {
public function __construct() {
}

protected function dostuff() {
 print "Hello World";
}
}

class bar extends foo {
public function __construct() {
 parent::__construct();
 $this->dostuff();
}
}

$x = new bar();
?>

 

Question 2) What are the deciding factors for when to make a function or attribute static?  How do you make that decision?

When you want it to belong to the whole class and not a specific instance of a class (object). i.e

<?php
class foo {
protected static $counter = 0;
public $num;

public function __construct() {
self::$counter++;
$this->num = self::$counter;
}
}
// same class - 2 individual objects
$x = new foo();
print $x->num."<br />"; // prints 1
$y = new foo();
print $y->num."<br />"; // prints 2
?>

 

This essentially means that the static property or method means something to the class but not to the individual object. i.e

<?php
class foo {
public static function convertLbToKg($pounds) {
 return $pounds * 0.45359;
}
}


class bar {
public $kg;
public function __construct($pounds) {
$this->kg = foo::convertLbToKg($pounds);
}
}


// I can call the static method from outside of the class
print foo::convertLbToKg(120)."kg<br />";
// Or it can be called from within another class when creating an object
$x = new bar(150);
print $x->kg."kg<br />";
?>

 

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