Php class call private method
INSIDE CODE and OUTSIDE CODE
class Item
/**
* This is INSIDE CODE because it is written INSIDE the class.
*/
public $label ;
public $price ;
>
/**
* This is OUTSIDE CODE because it is written OUTSIDE the class.
*/
$item = new Item ();
$item -> label = ‘Ink-Jet Tatoo Gun’ ;
$item -> price = 49.99 ;
?>
Ok, that’s simple enough. I got it inside and out. The big problem with this is that the Item class is COMPLETELY IGNORANT in the following ways:
* It REQUIRES OUTSIDE CODE to do all the work AND to know what and how to do it — huge mistake.
* OUTSIDE CODE can cast Item properties to any other PHP types (booleans, integers, floats, strings, arrays, and objects etc.) — another huge mistake.
Note: we did it correctly above, but what if someone made an array for $price? FYI: PHP has no clue what we mean by an Item, especially by the terms of our class definition above. To PHP, our Item is something with two properties (mutable in every way) and that’s it. As far as PHP is concerned, we can pack the entire set of Britannica Encyclopedias into the price slot. When that happens, we no longer have what we expect an Item to be.
INSIDE CODE should keep the integrity of the object. For example, our class definition should keep $label a string and $price a float — which means only strings can come IN and OUT of the class for label, and only floats can come IN and OUT of the class for price.
class Item
/**
* Here’s the new INSIDE CODE and the Rules to follow:
*
* 1. STOP ACCESS to properties via $item->label and $item->price,
* by using the protected keyword.
* 2. FORCE the use of public functions.
* 3. ONLY strings are allowed IN & OUT of this class for $label
* via the getLabel and setLabel functions.
* 4. ONLY floats are allowed IN & OUT of this class for $price
* via the getPrice and setPrice functions.
*/
protected $label = ‘Unknown Item’ ; // Rule 1 — protected.
protected $price = 0.0 ; // Rule 1 — protected.
public function getLabel () < // Rule 2 - public function.
return $this -> label ; // Rule 3 — string OUT for $label.
>
public function getPrice () < // Rule 2 - public function.
return $this -> price ; // Rule 4 — float OUT for $price.
>
public function setLabel ( $label ) // Rule 2 — public function.
/**
* Make sure $label is a PHP string that can be used in a SORTING
* alogorithm, NOT a boolean, number, array, or object that can’t
* properly sort — AND to make sure that the getLabel() function
* ALWAYS returns a genuine PHP string.
*
* Using a RegExp would improve this function, however, the main
* point is the one made above.
*/
if( is_string ( $label ))
$this -> label = (string) $label ; // Rule 3 — string IN for $label.
>
>
public function setPrice ( $price ) // Rule 2 — public function.
/**
* Make sure $price is a PHP float so that it can be used in a
* NUMERICAL CALCULATION. Do not accept boolean, string, array or
* some other object that can’t be included in a simple calculation.
* This will ensure that the getPrice() function ALWAYS returns an
* authentic, genuine, full-flavored PHP number and nothing but.
*
* Checking for positive values may improve this function,
* however, the main point is the one made above.
*/
if( is_numeric ( $price ))
$this -> price = (float) $price ; // Rule 4 — float IN for $price.
>
>
>
?>
Now there is nothing OUTSIDE CODE can do to obscure the INSIDES of an Item. In other words, every instance of Item will always look and behave like any other Item complete with a label and a price, AND you can group them together and they will interact without disruption. Even though there is room for improvement, the basics are there, and PHP will not hassle you. which means you can keep your hair!
If you have problems with overriding private methods in extended classes, read this:)
The manual says that «Private limits visibility only to the class that defines the item». That means extended children classes do not see the private methods of parent class and vice versa also.
As a result, parents and children can have different implementations of the «same» private methods, depending on where you call them (e.g. parent or child class instance). Why? Because private methods are visible only for the class that defines them and the child class does not see the parent’s private methods. If the child doesn’t see the parent’s private methods, the child can’t override them. Scopes are different. In other words — each class has a private set of private variables that no-one else has access to.
A sample demonstrating the percularities of private methods when extending classes:
abstract class base <
public function inherited () <
$this -> overridden ();
>
private function overridden () <
echo ‘base’ ;
>
>
class child extends base <
private function overridden () <
echo ‘child’ ;
>
>
$test = new child ();
$test -> inherited ();
?>
Output will be «base».
If you want the inherited methods to use overridden functionality in extended classes but public sounds too loose, use protected. That’s what it is for:)
A sample that works as intended:
abstract class base <
public function inherited () <
$this -> overridden ();
>
protected function overridden () <
echo ‘base’ ;
>
>
class child extends base <
protected function overridden () <
echo ‘child’ ;
>
>
$test = new child ();
$test -> inherited ();
?>
Output will be «child».
Calling private/protected PHP methods
Generally, private or protected methods should not be accessible outside the class. But if you’re writing a unit test, you can break this rule.
Given PHP class with private method:
class Foo private function bar(): string return 'baz'; > > Reflection
Use Reflection to call the method outside the class:
$reflectionClass = new ReflectionClass(Foo::class); $reflectionMethod = $reflectionClass->getMethod('bar'); $reflectionMethod->setAccessible(true); $reflectionMethod->invoke(new Foo()); // 'baz' Reflection works for both private and protected methods.
Alternatively, this can be refactored and simplified to ReflectionMethod :
$reflectionMethod = new ReflectionMethod(Foo::class, 'bar'); $reflectionMethod->setAccessible(true); $reflectionMethod->invoke(new Foo()); // 'baz' $args = [1, 2, 3]; $reflectionMethod->invokeArgs(new Foo(), $args); Here’s a reusable function that calls a class instance method:
/** * Calls object method with arguments. * * @param object $object * @param string $method * @param array $args * @return mixed */ function callObjectMethod(object $object, string $method, array $args = []) $reflectionMethod = new ReflectionMethod(get_class($object), $method); $reflectionMethod->setAccessible(true); return $reflectionMethod->invokeArgs($object, $args); > This means you can call Foo::bar :
callObjectMethod(new Foo(), 'bar'); // 'baz' Demo
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PHP — Calling Private Function within the Class Displaying MySQL Data
I have a class Club<> that has several public functions and private functions. The three private functions I have are used to get data from my database. Here is the following code:
private function Get_Members_From_DB() < $sql = "SELECT Email, FirstName, LastName, Gender FROM member"; $result = mysqli_query($this->Con, $sql); $arrayResult = array(); while($row = mysqli_fetch_array($result)) < $arrayResult[] = $row; >return ($arrayResult); > private function Get_Members_Interests_From_DB($MemberEmail) < $sql = "SELECT interest_type.InterestDescription FROM member, member_interests, interest_type WHERE member.Email = '$MemberEmail' AND member.Email = member_interests.Email AND member_interests.InterestID = interest_type.InterestID"; $result = mysqli_query($this->Con, $sql); while($row = mysqli_fetch_array($result)) < $arrayResult[] = $row; >return ($arrayResult); > private function Get_Interests_Types_From_DB() < $sql = "SELECT InterestID, InterestDescription FROM interest_type"; $result = mysqli_query($this->Con, $sql); while($row = mysqli_fetch_array($result)) < $arrayResult[] = $row; >return ($arrayResult); > When I call these, I get Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given on line 406, which is while($row = mysqli_fetch_array($result)) . I also get Fatal error: Cannot use object of type Club as array in on line 48 which is echo(«
- ;»); $results2 = new Club; $results2->Get_Members_Interests_From_DB($row1[‘Email’]); while($row2 = mysqli_fetch_array($results2)) < $interests[] = $row2; echo("
- » . $row2[‘InterestDescription’] . «»); > echo(«
$sql = "SELECT Email, FirstName, LastName, Gender FROM member"; $result = mysqli_query($this->Con, $sql); return ($result); And it still does not work in the DisplayMembers() function with out getting the first error I posted above, except it would be on line 46, which would be changed to: while($row1 = mysqli_fetch_array($members)) If I take the above code and paste it directly into DisplayMembers() I can get the function to display correctly as an HTML table. I do not understand why I am getting errors when I separate the code into the private function. Any ideas? EDIT: I am calling these private functions from a public function inside the SAME class.