I have the simplest bit of code :
Interface
interface iCrudRepository{
public function Create($id);
public function Read($id);
public function Update($id);
public function Delete($id);
}
Parent
class Repository
{
function __construct()
{
echo "SHOULD NOT BE CALLED AUTOMATICALLY";
}
}
Class
require_once(__DIR__.'/../injection/bootstrap.php');
class Admin extends Repository implements iCrudRepository
{
function Create($id)
{
}
function Read($id)
{
}
function Update($id)
{
}
function Delete($id)
{
}
}
$admin = new Admin();
$admin->Create("Something");
The bootstrap class autoloads my classes via the spl_autoload_register function. Since in the Admin class I don't call the parent constructor, it shouldn't execute what is in the parent's constructor right?
The Output
SHOULD NOT BE CALLED AUTOMATICALLY
Probably missing something obvious here but can't quite figure out why it is called.
Docs state:
Parent constructors are not called implicitly if the child class
defines a constructor.
So you have to do this in order to prevent what you are seeing:
class Admin extends Repository implements iCrudRepository
{
public function __construct()
{
}
function Create($id)
{
}
function Read($id)
{
}
function Update($id)
{
}
function Delete($id)
{
}
}
I cant manage to call a static function (with a constant) from a extended class. Here is my code:
(1st file)
class A
{
function isXSet()
{
return X;
}
public static function setX()
{
define('X', 1);
}
}
(second file)
include('/*first file*/');
class B extends A
{
A::setX();
}
How can i manage to do that ?
Your code here
class B extends A
{
A::setX();
}
is a little off. You didn't put your call inside of a method.
class B extends A
{
public static function doSomething() {
A::setX();
}
}
This isn't actually doing anything by means of the parent/child relationship. In fact, after you define class A, the call to A::setX() can happen anywhere since it's public and static. This code is just as valid:
class A
{
function isXSet()
{
return X;
}
public static function setX()
{
define('X', 1);
}
}
class B { // No extending!
function isXSet() {
return A::isXSet();
}
}
What you're more likely looking for is parent instead:
class A
{
public function isXSet()
{
return X;
}
protected static function setX()
{
define('X', 1);
}
}
class B extends A
{
public static function doSomething() {
parent::setX();
var_dump( parent::isXSet() ); // int(1)
}
}
A big plus here is that extending classes can access protected methods and properties from the parent class. This means you could keep everyone else from being able to call A::setX() unless the callee was an instance of or child of A.
To be specific, i have a two class Request and Utils,
class Request
{
public function __construct()
{
//constructor method
}
public function request()
{
$utils=new Utils;
$consolidated_errors=$utils->array_remove_empty($all_params_error);
}
public function process()
{
$utils=new Utils;
$consolidated_errors=$utils->another_method($all_params_error);
}
}
And class Utils,
class Utils
{
public function __construct()
{
//constructor method
}
public function array_remove_empty()
{
//returns a variable.
}
public function another_method()
{
//returns a variable.
}
}
you can see that i am initializing the class two times in request class , and my question is that any way initializing the class globally and using through out the class?
You are looking for Singleton pattern
Following demonstrate very basic Singleton example for your class
public class Utils {
private static Utils uniqInstance;
private Utils() {
}
public static synchronized Utils getInstance() {
if (uniqInstance == null) {
uniqInstance = new Utils();
}
return uniqInstance;
}
// other useful methods here
}
get the instance using static-factory pattern
The above code does not look like Java to me, but anyway,
You could create the class at a class level private Utils myUtuils = new Utils ();
or
have the class as a static class and then just use it directly in your method
public function process()
{
consolidated_errors= Utils.another_method($all_params_error);
}
}
I have a base class A:
class A {
public static function a() {
...
}
public static function b() {
...
}
}
and an extended class B
class B extends A {
public static function a() {
...
}
public static function c() {
...
}
}
I would like to be able to call all the methods using B::
How would I call A::b, using B::?
You should be able to accomplish this as easily as:
class B extends A {
public static function a() {
parent::a();
}
}
See the docs
I need to have a class constructor in PHP call its parent's parent's (grandparent?) constructor without calling the parent constructor.
// main class that everything inherits
class Grandpa
{
public function __construct()
{
}
}
class Papa extends Grandpa
{
public function __construct()
{
// call Grandpa's constructor
parent::__construct();
}
}
class Kiddo extends Papa
{
public function __construct()
{
// THIS IS WHERE I NEED TO CALL GRANDPA'S
// CONSTRUCTOR AND NOT PAPA'S
}
}
I know this is a bizarre thing to do and I'm attempting to find a means that doesn't smell bad but nonetheless, I'm curious if it's possible.
The ugly workaround would be to pass a boolean param to Papa indicating that you do not wish to parse the code contained in it's constructor. i.e:
// main class that everything inherits
class Grandpa
{
public function __construct()
{
}
}
class Papa extends Grandpa
{
public function __construct($bypass = false)
{
// only perform actions inside if not bypassing
if (!$bypass) {
}
// call Grandpa's constructor
parent::__construct();
}
}
class Kiddo extends Papa
{
public function __construct()
{
$bypassPapa = true;
parent::__construct($bypassPapa);
}
}
You must use Grandpa::__construct(), there's no other shortcut for it. Also, this ruins the encapsulation of the Papa class - when reading or working on Papa, it should be safe to assume that the __construct() method will be called during construction, but the Kiddo class does not do this.
class Grandpa
{
public function __construct()
{}
}
class Papa extends Grandpa
{
public function __construct()
{
//call Grandpa's constructor
parent::__construct();
}
}
class Kiddo extends Papa
{
public function __construct()
{
//this is not a bug, it works that way in php
Grandpa::__construct();
}
}
Beautiful solution using Reflection.
<?php
class Grandpa
{
public function __construct()
{
echo "Grandpa's constructor called\n";
}
}
class Papa extends Grandpa
{
public function __construct()
{
echo "Papa's constructor called\n";
// call Grandpa's constructor
parent::__construct();
}
}
class Kiddo extends Papa
{
public function __construct()
{
echo "Kiddo's constructor called\n";
$reflectionMethod = new ReflectionMethod(get_parent_class(get_parent_class($this)), '__construct');
$reflectionMethod->invoke($this);
}
}
$kiddo = new Kiddo();
$papa = new Papa();
I ended up coming up with an alternative solution that solved the problem.
I created an intermediate class that extended Grandpa.
Then both Papa and Kiddo extended that class.
Kiddo required some intermediate functionality of Papa but didn't like it's constructor so the class has that additional functionality and both extend it.
I've upvoted the other two answers that provided valid yet ugly solutions for an uglier question:)
Another option that doesn't use a flag and might work in your situation:
<?php
// main class that everything inherits
class Grandpa
{
public function __construct(){
$this->GrandpaSetup();
}
public function GrandpaSetup(){
$this->prop1 = 'foo';
$this->prop2 = 'bar';
}
}
class Papa extends Grandpa
{
public function __construct()
{
// call Grandpa's constructor
parent::__construct();
$this->prop1 = 'foobar';
}
}
class Kiddo extends Papa
{
public function __construct()
{
$this->GrandpaSetup();
}
}
$kid = new Kiddo();
echo "{$kid->prop1}\n{$kid->prop2}\n";
I agree with "too much php", try this:
class Grandpa
{
public function __construct()
{
echo 'Grandpa<br/>';
}
}
class Papa extends Grandpa
{
public function __construct()
{
echo 'Papa<br/>';
parent::__construct();
}
}
class Kiddo extends Papa
{
public function __construct()
{
// THIS IS WHERE I NEED TO CALL GRANDPA'S
// CONSTRUCTOR AND NOT PAPA'S
echo 'Kiddo<br/>';
Grandpa::__construct();
}
}
$instance = new Kiddo;
I got the result as expected:
Kiddo
Grandpa
This is a feature not a bug, check this for your reference:
https://bugs.php.net/bug.php?id=42016
It is just the way it works. If it sees it is coming from the right context this call version does not enforce a static call.
Instead it will simply keep $this and be happy with it.
parent::method() works in the same way, you don't have to define the method as static but it can be called in the same context. Try this out for more interesting:
class Grandpa
{
public function __construct()
{
echo 'Grandpa<br/>';
Kiddo::hello();
}
}
class Papa extends Grandpa
{
public function __construct()
{
echo 'Papa<br/>';
parent::__construct();
}
}
class Kiddo extends Papa
{
public function __construct()
{
// THIS IS WHERE I NEED TO CALL GRANDPA'S
// CONSTRUCTOR AND NOT PAPA'S
echo 'Kiddo<br/>';
Grandpa::__construct();
}
public function hello()
{
echo 'Hello<br/>';
}
}
$instance = new Kiddo;
It also works as expected:
Kiddo
Grandpa
Hello
But if you try to initialize a new Papa, you will get an E_STRICT error:
$papa = new Papa;
Strict standards: Non-static method Kiddo::hello() should not be called statically, assuming $this from incompatible context
You can use instanceof to determine if you can call a Children::method() in a parent method:
if ($this instanceof Kiddo) Kiddo::hello();
There's an easier solution for this, but it requires that you know exactly how much inheritance your current class has gone through. Fortunately, get_parent_class()'s arguments allow your class array member to be the class name as a string as well as an instance itself.
Bear in mind that this also inherently relies on calling a class' __construct() method statically, though within the instanced scope of an inheriting object the difference in this particular case is negligible (ah, PHP).
Consider the following:
class Foo {
var $f = 'bad (Foo)';
function __construct() {
$this->f = 'Good!';
}
}
class Bar extends Foo {
var $f = 'bad (Bar)';
}
class FooBar extends Bar {
var $f = 'bad (FooBar)';
function __construct() {
# FooBar constructor logic here
call_user_func(array(get_parent_class(get_parent_class($this)), '__construct'));
}
}
$foo = new FooBar();
echo $foo->f; #=> 'Good!'
Again, this isn't a viable solution for a situation where you have no idea how much inheritance has taken place, due to the limitations of debug_backtrace(), but in controlled circumstances, it works as intended.
You can call Grandpa::__construct from where you want and the $this keyword will refer to your current class instance. But be carefull with this method you cannot access to protected properties and methods of current instance from this other context, only to public elements. => All work and officialy supported.
Example
// main class that everything inherits
class Grandpa
{
public function __construct()
{
echo $this->one; // will print 1
echo $this->two; // error cannot access protected property
}
}
class Papa extends Grandpa
{
public function __construct()
{
// call Grandpa's constructor
parent::__construct();
}
}
class Kiddo extends Papa
{
public $one = 1;
protected $two = 2;
public function __construct()
{
Grandpa::__construct();
}
}
new Kiddo();
Funny detail about php: extended classes can use non-static functions of a parent class in a static matter. Outside you will get a strict error.
error_reporting(E_ALL);
class GrandPa
{
public function __construct()
{
print("construct grandpa<br/>");
$this->grandPaFkt();
}
protected function grandPaFkt(){
print(">>do Grandpa<br/>");
}
}
class Pa extends GrandPa
{
public function __construct()
{ parent::__construct();
print("construct Pa <br/>");
}
public function paFkt(){
print(">>do Pa <br>");
}
}
class Child extends Pa
{
public function __construct()
{
GrandPa::__construct();
Pa::paFkt();//allright
//parent::__construct();//whatever you want
print("construct Child<br/>");
}
}
$test=new Child();
$test::paFkt();//strict error
So inside a extended class (Child) you can use
parent::paFkt();
or
Pa::paFkt();
to access a parent (or grandPa's) (not private) function.
Outside class def
$test::paFkt();
will trow strict error (non static function).
<?php
class grand_pa
{
public function __construct()
{
echo "Hey I am Grand Pa <br>";
}
}
class pa_pa extends grand_pa
{
// no need for construct here unless you want to do something specifically within this class as init stuff
// the construct for this class will be inherited from the parent.
}
class kiddo extends pa_pa
{
public function __construct()
{
parent::__construct();
echo "Hey I am a child <br>";
}
}
new kiddo();
?>
Of course this expects you do not need to do anything within the construct of the pa_pa. Running this will output :
Hey I am Grand Pa
Hey I am a child
Ok, Yet another ugly solution:
Create a function in Papa like:
protected function call2Granpa() {
return parent::__construct();
}
Then in Kiddo you use:
parent::call2Granpa(); //instead of calling constructor in Papa.
I think it could work... I haven't test it, so I'm not sure if the
objects are created correctly.
I used this approach but with non-constructor functions.
// main class that everything inherits
class Grandpa
{
public function __construct()
{
$this->___construct();
}
protected function ___construct()
{
// grandpa's logic
}
}
class Papa extends Grandpa
{
public function __construct()
{
// call Grandpa's constructor
parent::__construct();
}
}
class Kiddo extends Papa
{
public function __construct()
{
parent::___construct();
}
}
note that "___construct" is not some magic name, you can call it "doGrandpaStuff".
class Grandpa
{
public function __construct()
{
echo"Hello Kiddo";
}
}
class Papa extends Grandpa
{
public function __construct()
{
}
public function CallGranddad()
{
parent::__construct();
}
}
class Kiddo extends Papa
{
public function __construct()
{
}
public function needSomethingFromGrandDad
{
parent::CallGranddad();
}
}
from php 7 u can use
parent::parent::__construct();