I wan't to execute constructor in my trait (or another method while trait is used). Is it possible?
trait test{
public function __construct()
{
echo 'test';
}
}
class myClass{
use test;
public function __construct(){
echo 'myClass';
}
}
new myClass();
Try it like this (test):
trait test{
public function __construct()
{
echo 'test';
}
}
class myClass{
use test {
test::__construct as private __tConstruct;
}
public function __construct(){
$this->__tConstruct();
}
}
new myClass();
I'm a bit rusty with php, I want to know how I can call the function login available in class2, inside class1. This is the example:
<?php
require_once("property2.php");
class Class1
{
public function __construct()
{
$cls2 = new Class2()
}
public function method1()
{
$cls2->login() //cl2 is undefined
}
} ..
//this is the function
...
class Class2
{
public function __construct()
{
}
//This is the function to call
public function login()
{
//Some stuff
}
} ...
Now PHPSTORM say that the variable cls2 is undefined. What I did wrong?
When you are setting your variable youre not setting it as a class property. Define a private variable inside your class, and "set it and get it" using the $this keyword.
class Class1 {
private $cls2;
public function __construct() {
$this->cls2 = new Class2();
}
public function method1() {
$this->cls2->login();
}
}
Another way to achieve this is to use Inheritance, where one class is considered a "parent" class. You would achieve this by using extends
class Class1 {
public function __construct() {
//Some stuff
}
public function login() {
//Some stuff
}
}
class Class2 extends Class1 {
public function __construct() {
parent::__construct();
}
public function method1() {
$this->login();
}
}
class Class1
{
public function __construct()
{
$cls2 = new Class2();
}
public function method1()
{
$cls2->login() //cl2 is undefined
}
}
When you create Class1 and call $cls2 = new Class2();, $cls2 exists only locally. You have to make it a class property:
class Class1
{
public $cls2;
public function __construct()
{
$this->cls2 = new Class2();
}
public function method1()
{
$this->cls2->login();
}
}
And then you'll be able to access it using $this keyword.
Also please watch for semicolons.
<?php
class BaseController extends Controller
{
protected $foo;
public function __construct()
{
$this->foo = '123';
}
protected function setupLayout()
{
if ( ! is_null($this->layout))
{
$this->layout = View::make($this->layout);
}
}
}
Above is the BaseController and I want to declare foo as 123, but can I get the foo variable in the controller which I have extended from this basecontroller, can you help?
public function detail($action)
{
return $this->foo;
}
As per docs:
http://php.net/manual/en/language.oop5.decon.php
Note: Parent constructors are not called implicitly if the child class
defines a constructor. In order to run a parent constructor, a call to
parent::__construct() within the child constructor is required.
As you are doing some work in your parent class constructor, you must invoke it directly in your subclass too (even this would be to only thing you do in child's constructor). I.e.:
class ChildController extends BaseController
{
public function __construct() {
parent::__construct();
}
...
When you extend the controller, I imagine that you're currently doing this:
<?php
class NewController extends BaseController
{
public function __construct()
{
// Do something here.
}
public function detail($action)
{
return $this->foo;
}
}
You see how the __construct method is being overwritten. You can easily fix this by adding parent::__construct() to the beginning of the method, so you'll have this:
<?php
class NewController extends BaseController
{
public function __construct()
{
parent::__construct();
// Do something here.
}
public function detail($action)
{
return $this->foo;
}
}
How Can i call subclass method from superclass constructor?
Example subclass:
<?php
include('../classes/A.php');
class B extends A {
public function __construct()
{
parent::__construct($this->view);
}
public function view() {
//something
}
}
$b = new B;
?>
Example superclass:
<?php
abstract class A
{
private $callback;
public function __construct($callback)
{
$this->callback = $callback;
call_user_func($this->callback);
}
}
?>
What can I do to make it works?
Pass an array containing your object instance $this, and the method to call
(see Example #4 of the call_user_func man page on calling class methods)
class B extends A {
public function __construct()
{
parent::__construct(array($this, 'view'));
}
public function view() {
//something
}
}
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();