I have object $obj (class A).
Can I convert class for $obj to B?
Perhaps there is another way.
Example:
class A
{
public $AProp = 1;
public function &Convert($ATypeName)
{
// HOW?
return $this;
}
}
class B extends A
{
public $BProp = 2;
}
$obj=new A();
$obj->Convert("B");
print_r($obj->BProp);
I wrote next solution, but it is no good.
(It looks like your post is mostly code; I add some more details)
class A
{
public $AProp = 1;
public function &Convert($ATypeName)
{
$Result = new $ATypeName; // Create new object
$Result->AProp = $this->AProp; // Copy params...
return $Result;
}
}
class B extends A
{
public $BProp = 2;
}
$obj = new A();
$obj->AProp = 3;
$obj = $obj->Convert("B");
print_r($obj);
u are trying to use c++-way of class extending.
the php-way is smth like this:
<?php
class A
{
protected $prop = 1;
public function getProp()
{
return $this->prop;
}
}
class B extends A
{
protected $prop = 2;
}
$obj=new A();
print_r($obj->getProp());
$obj=new B();
print_r($obj->getProp());
also take a look on late static bindings - http://php.net/manual/en/language.oop5.late-static-bindings.php
<?php
class A
{
public static $prop = 1;
public function getProp()
{
return static::$prop;
}
}
class B extends A
{
public static $prop = 2;
}
$obj=new A();
print_r($obj->getProp());
$obj=new B();
print_r($obj->getProp());
This is the only way:
$obj = new B();
Since inheritance is used you can access all class A func and var, like $this->Aprop
Related
I would like to bind a function (a method of a class) to another class. Any idea of how i could achieve this?
Here is an example of what i want:
class A {
protected $prop = "prop A";
function method($arg1, ...) {
return $this->prop;
}
}
class B {
protected $prop = "prop B";
// need help here
}
So i want to "bind" the method "method" of class "A" to class "B" so it'll be possible to do $b = new B(); $b->method($arg1, ...); and obtain "prop B";
Thanks in advance!!
I tried:
class B {
protected $instance;
protected $prop = "prop B";
public function __construct($instance) {
$this->instance = $instance;
}
public function __call($method, $args) {
return call_user_func_array([$this->instance, $method], $args);
}
}
$b = new B(new A());
$b->method();
But still outputing "prop A";
I tried this too:
class B {
protected $prop = "prop B";
public function __call($method, $args) {
return call_user_func_array(Closure::bind($this->$method, $this, get_called_class()), $arguments);
}
}
$a = new A();
$b = new B();
$b->method = $a->method;
$b->method();
But i'm getting this error: Closure::bind() expects parameter 1 to be Closure, null given....
At last i tried this too:
class B {
protected $instance;
protected $prop = "prop B";
public function __construct($instance) {
$this->instance = $instance;
}
public function __call($method, $args) {
$new_method = $this->instance->$method->bindTo($this);
return call_user_func_array($new_method, $args);
}
}
$b = new B(new A());
$b->method();
Here, an error says $this->instance->$method is null
Using dependency injection, you can access the passed object:
class A {
public function speak() { return ‘meow’; }
}
class B {
public function __construct($obj) {
$this->a = $obj;
}
}
$demo = new B( new A));
print $demo->a->speak();
// => meow
From here, if you want B->speak to refer to A->speak:
class A {
public function speak() { return ‘meow’; }
}
class B {
public function __construct($obj) {
$this->a = $obj;
}
public function speak() {
return $this->a->speak();
}
}
$demo = new B( new A));
print $demo->a->speak(); // meow
print $demo->speak(); // meow
Or, if B is a special kind of A:
// use obj A above
class B extends A {
// do stuff B knows
}
$demo = new B;
print $demo->speak();
// => meow
If you’re wanting the exact same method in both classes, perhaps what you’re looking for is traits. Traits are more or less an include for objects which lets objects “share” code. (Personally I think it’s a fancy way of violating DRY and is better handled with DI... but smarter people than I have included it in the language)
Using traits would be something like this (double check docs, I’ve never used this)
trait sharedMethod {
public function speak() {
return $this->prop;
}
}
class A {
use sharedMethod;
public $prop = “I’m from A”;
}
class B {
use sharedMethod;
public $prop = “I’m from B”;
public function __construct(object $a) {
$this->a = $a;
}
/**
* use this to get A’s method, or omit to keep B’s method
*/
public function speak() {
return $this->a->speak();
}
}
$demo = new B( new A));
print $demo->speak(); // I’m from A
// if you don’t override the method
$demo = new B( new A));
print $demo->speak(); // I’m from B
I have 3 classes:
Class A - Parent Class
Class B - Child Class
Class C - Class to be used in Class A
I want to use functions from class C using variables from my Child class.
<?php
class A
{
public function __construct()
{
$this->load();
}
public function load()
{
$class = new C();
$class->test = $this->test;
$this->c = $class;
}
}
class B extends A
{
public function __construct()
{
parent::__construct();
}
}
class C
{
public function display()
{
echo $this->test;
}
}
$b = new B();
$b->test = 1;
$b->c->display();
Your problem is here:
$class->test = $this->test;
You are attempting to use a property that is not yet defined, because when you do this:
$b->test = 1;
the constructor has already been called, and there's nothing in your classes to update C with the value of B's test property.
You can solve this in a couple of different ways.
1) Send the value in B's constructor, and pass it down the entire chain:
class A
{
public function __construct($test)
{
$this->load($test);
}
public function load($test)
{
$class = new C();
$class->test = $test;
$this->c = $class;
}
}
class B extends A
{
public function __construct($test)
{
parent::__construct($test);
}
}
class C
{
public function display()
{
echo $this->test;
}
}
$b = new B(123);
$b->c->display();
2) Add a method to B that will update C's property:
<?php
class A
{
public function __construct()
{
$this->load();
}
public function load()
{
$class = new C();
$this->c = $class;
}
}
class B extends A
{
public function __construct()
{
parent::__construct();
}
public function setTest($test)
{
$this->c->test = $test;
}
}
class C
{
public function display()
{
echo $this->test;
}
}
$b = new B();
$b->setTest(123);
$b->c->display();
Or perhaps a combination of both.
I try to create object in PHP class, but i get some interesting errors in IDE, like unexpected ( token etc. Here is my code:
class A {
public $a = 1;
}
class B {
$aa = new A();
}
Where is the problem?
In PHP, you can only assign "fixed" values to properties in the class definition.
class A {
public $a = 3; // will work
public $b = "hello"; // will work
public $c = foo(); // won't work
public $d = new Foo(); // won't work
}
If you want to do so, you can use the __construct() method which will be called every time a new instance is created or any other method that you call.
class B {
public $aa; // define visibility of $aa
function __construct() {
$this->aa = new A();
}
}
You need to make a constructor on class A
class A {
function __construct() {
$this->a = 1;
}
public function returnA() {
return $this->a;
}
}
$aa = new A();
echo $aa->returnA();
Try to create a constructor in class A and see if it works:
class A {
public $a;
function __construct()
{
$this->$a = 1;
}
}
class B {
$aa = new A();
}
Is it possible to declare an object inside another class? The following code keeps giving me an error nexpected 'new' (T_NEW) error.
Class class1{
public function doSomething(){
$var = 3;
return true;
}
}
Class class2{
public $class1 = new class1();
public function doSomethingElse(){
if($class1->doSomething() == true){
return 10;
}else{
return 13;
}
}
}
//$obj = new class2();
I don't really want want to pass in the object through a constructor, because it's used inside other classes, so I'd have to pass it through multiple times. Is there a better method?
Use the Constructor of your class to instantiate the other class.
Class class1
{
public function doSomething()
{
$var = 3;
return true;
}
}
Class class2
{
protected $class1 = null;
public function __construct()
{
$this->class1 = new class1();
}
public function doSomethingElse()
{
if ($this->class1->doSomething() == true) {
return 10;
} else {
return 13;
}
}
}
Yes, but you have to put the initialization in construction method.
Class class2{
public $class1;
public function __construct() {
$this->class1 = new class1();
}
// ...
}
You can only initialize scalar values and arrays, use the constructor:
class Class2 {
public $class1;
public function __construct() {
$this->class1 = new Class1();
}
...
}
we have two class A & B:
class A{
var $settings;
function getinfo(){
$settings['domain']="mydomain";
$settings['pass']="1234";
return $settings;
}
}
class B extends A{
$ads = A::getinfo();
function makeurl(){
return "template/".$ads['domain'];
}
}
now i have an instance of B in my page, but i need "pass" , maybe some code like this:
$theme=new B();
$mypass = $theme->A->getinfo;
echo $mypass[$pass];
I know this code is full of faults , but i could not write a better one. is there any solution to access to password without making an instance of A?
Yes. It is as simple as this:
$theme = new B();
$mypass = $theme->getinfo();
echo $mypass['pass'];
You can also improve your classes a bit:
class A
{
var $settings;
function getinfo()
{
$this->settings['domain'] = "mydomain";
$this->settings['pass'] = "1234";
return $this->settings;
}
}
class B extends A
{
function makeurl()
{
$this->getinfo();
return 'template/' . $this->settings['domain'];
}
}
Why not call the settings variable in A from the B instance since B is a subclass of A?
Try this code:
<?php
class A
{
var $settings;
function getinfo()
{
$settings['domain'] = "mydomain";
$settings['pass'] = "1234";
return $settings;
}
}
class B extends A
{
function makeurl()
{
$ads = $this->getinfo();
return "template/" . $ads['domain'];
}
}
$theme=new B();
$mypass = $theme->getinfo();
echo $mypass['pass'];
What about making settings a public static variable in A? By making it a class variable you won't need an instance of A.
class A {
public static $settings;
// getter and setter methods here
}
// code elsewhere
echo A::$settings['pass'];
Also because your class B extends A it inherits the methods and properties, so you could call
$theme = new B();
$mySettings = $theme->GetInfo();
if B extends A, all protected and public members of A are inherited into B, so you can access them directly.
class A {
protected $foo;
public function __construct() { $this->foo = 1; }
}
class B extends A {
public function bar() {
echo $this->foo;
}
}
$b = B();
$b->bar();
If I understand you correctly, you're pretty close:
$theme=new B();
$settings = $theme->getinfo();
$mypass = $settings['pass'];
echo $mypass;