How can I create a property from a given argument inside a object's method?
class Foo{
public function createProperty($var_name, $val){
// here how can I create a property named "$var_name"
// that takes $val as value?
}
}
And I want to be able to access the property like:
$object = new Foo();
$object->createProperty('hello', 'Hiiiiiiiiiiiiiiii');
echo $object->hello;
Also is it possible that I could make the property public/protected/private ? I know that in this case it should be public, but I may want to add some magik methods to get protected properties and stuff :)
I think I found a solution:
protected $user_properties = array();
public function createProperty($var_name, $val){
$this->user_properties[$var_name] = $val;
}
public function __get($name){
if(isset($this->user_properties[$name])
return $this->user_properties[$name];
}
do you think it's a good idea?
There are two methods to doing it.
One, you can directly create property dynamically from outside the class:
class Foo{
}
$foo = new Foo();
$foo->hello = 'Something';
Or if you wish to create property through your createProperty method:
class Foo{
public function createProperty($name, $value){
$this->{$name} = $value;
}
}
$foo = new Foo();
$foo->createProperty('hello', 'something');
The following example is for those who do not want to declare an entire class.
$test = (object) [];
$prop = 'hello';
$test->{$prop} = 'Hiiiiiiiiiiiiiiii';
echo $test->hello; // prints Hiiiiiiiiiiiiiiii
Property overloading is very slow. If you can, try to avoid it. Also important is to implement the other two magic methods:
__isset();
__unset();
If you don't want to find some common mistakes later on when using these object "attributes"
Here are some examples:
http://www.php.net/manual/en/language.oop5.overloading.php#language.oop5.overloading.members
EDITED after Alex comment:
You can check yourself the differences in time between both solutions (change $REPEAT_PLEASE)
<?php
$REPEAT_PLEASE=500000;
class a {}
$time = time();
$a = new a();
for($i=0;$i<$REPEAT_PLEASE;$i++)
{
$a->data = 'hi';
$a->data = 'bye'.$a->data;
}
echo '"NORMAL" TIME: '.(time()-$time)."\n";
class b
{
function __set($name,$value)
{
$this->d[$name] = $value;
}
function __get($name)
{
return $this->d[$name];
}
}
$time=time();
$a = new b();
for($i=0;$i<$REPEAT_PLEASE;$i++)
{
$a->data = 'hi';
//echo $a->data;
$a->data = 'bye'.$a->data;
}
echo "TIME OVERLOADING: ".(time()-$time)."\n";
Use the syntax: $object->{$property}
where $property is a string variable and
$object can be this if it is inside the class or any instance object
Live example: http://sandbox.onlinephpfunctions.com/code/108f0ca2bef5cf4af8225d6a6ff11dfd0741757f
class Test{
public function createProperty($propertyName, $propertyValue){
$this->{$propertyName} = $propertyValue;
}
}
$test = new Test();
$test->createProperty('property1', '50');
echo $test->property1;
Result: 50
How can I create a property from a given argument inside a object's method?
class Foo{
public function createProperty($var_name, $val){
// here how can I create a property named "$var_name"
// that takes $val as value?
}
}
And I want to be able to access the property like:
$object = new Foo();
$object->createProperty('hello', 'Hiiiiiiiiiiiiiiii');
echo $object->hello;
Also is it possible that I could make the property public/protected/private ? I know that in this case it should be public, but I may want to add some magik methods to get protected properties and stuff :)
I think I found a solution:
protected $user_properties = array();
public function createProperty($var_name, $val){
$this->user_properties[$var_name] = $val;
}
public function __get($name){
if(isset($this->user_properties[$name])
return $this->user_properties[$name];
}
do you think it's a good idea?
There are two methods to doing it.
One, you can directly create property dynamically from outside the class:
class Foo{
}
$foo = new Foo();
$foo->hello = 'Something';
Or if you wish to create property through your createProperty method:
class Foo{
public function createProperty($name, $value){
$this->{$name} = $value;
}
}
$foo = new Foo();
$foo->createProperty('hello', 'something');
The following example is for those who do not want to declare an entire class.
$test = (object) [];
$prop = 'hello';
$test->{$prop} = 'Hiiiiiiiiiiiiiiii';
echo $test->hello; // prints Hiiiiiiiiiiiiiiii
Property overloading is very slow. If you can, try to avoid it. Also important is to implement the other two magic methods:
__isset();
__unset();
If you don't want to find some common mistakes later on when using these object "attributes"
Here are some examples:
http://www.php.net/manual/en/language.oop5.overloading.php#language.oop5.overloading.members
EDITED after Alex comment:
You can check yourself the differences in time between both solutions (change $REPEAT_PLEASE)
<?php
$REPEAT_PLEASE=500000;
class a {}
$time = time();
$a = new a();
for($i=0;$i<$REPEAT_PLEASE;$i++)
{
$a->data = 'hi';
$a->data = 'bye'.$a->data;
}
echo '"NORMAL" TIME: '.(time()-$time)."\n";
class b
{
function __set($name,$value)
{
$this->d[$name] = $value;
}
function __get($name)
{
return $this->d[$name];
}
}
$time=time();
$a = new b();
for($i=0;$i<$REPEAT_PLEASE;$i++)
{
$a->data = 'hi';
//echo $a->data;
$a->data = 'bye'.$a->data;
}
echo "TIME OVERLOADING: ".(time()-$time)."\n";
Use the syntax: $object->{$property}
where $property is a string variable and
$object can be this if it is inside the class or any instance object
Live example: http://sandbox.onlinephpfunctions.com/code/108f0ca2bef5cf4af8225d6a6ff11dfd0741757f
class Test{
public function createProperty($propertyName, $propertyValue){
$this->{$propertyName} = $propertyValue;
}
}
$test = new Test();
$test->createProperty('property1', '50');
echo $test->property1;
Result: 50
This may be a bit of an XY questions, so I'm going to explain what I'm trying to do first. I'm attempting to create a single php file to handle all of my page refresh AJAX calls. That means I want to be able to send it a class name, plus a list of the variables that the class constructor takes, and for it to then create the class.
I can create the class fine. $class = new $className(); works just fine for creating the class. The problem is passing in the default variables. Most of the variables are objects containing other classes, so I can't just include this once the class is created, I need to pass them as the class is created.
I was thinking something along the lines of:
$varStr = '';
$s = '';
foreach($vars as $var) {
switch($var['type']) {
case 'object':
$varStr .= $s . '$' . $var['value'];
break;
case 'variable':
$varStr .= $s . $var['value'];
}
$s = ',';
}
$class = new $className(echo $varStr);
Now obviously echo $varStr isn't going to work there, but I have no idea what will. Is there anything I can do that will output the variables from my array into the class constructor like that? Is what I'm trying to do even possible? Is there a better way?
Whilst I understand I could just pass the whole array to the class constructor, this would complicate the main part of the program, and I would rather just ditch the idea of a single page for AJAX refresh than go down that route.
So basically you're trying to pass a variable number of arguments to a constructor? In a regular function, you could do something like:
function foo() {
$args = func_get_args();
...
}
call_user_func_array('foo', array('bar', 'baz'));
This won't work for constructors, since the calling mechanism is different. You could do:
class Foo {
public function __construct() {
$args = func_get_args();
...
}
}
$class = new ReflectionClass('Foo');
$obj = $class->newInstanceArgs(array('bar', 'baz'));
But really, what you should be doing is this:
class Foo {
public function __construct(array $args) {
...
}
}
$obj = new Foo(array('bar', 'baz'));
or
class Foo {
public function __construct($bar, $baz) {
...
}
}
$obj = new Foo('bar', 'baz');
Anything else is quite insane. If your object constructor is so complicated, you probably need to simplify it.
This is a wild guess at what you're trying to do but maybe this is what you're after:
// Generate constructor args
$args = array();
foreach($vars as $var) {
switch($var['type']) {
$value = $var['value'];
case 'object':
args[] = ${$value}; // evaluate, I think that's what you want?
break;
case 'variable':
args[] = $value; // use as is
break;
}
}
// Instanciate class with args
$class = new ReflectionClass($className);
$obj = $class->newInstanceArgs($args);
For this to work, it would require $vars to enumerates args in the correct order expected by each class constructor.
Unfortunately I cannot provide any code examples, however I will try and create an example.
My question is about Objects and memory allocation in PHP.
If I have an object, lets say:
$object = new Class();
Then I do something like
$object2 = $object;
What is this actualy doing? I know there is a clone function, but thats not what I'm asking about, I'm concerned about whether this is creating another identical object, or if its just assigning a reference to $object.
I strongly understand this to mean that it just creates a reference, but in some case usages of mine, I find that I get another $object created, and I can't understand why.
If you use the magic method __invoke, you can call an object similar to a function, and it will call that magic method.
class Object{
function __invoke(){ return "hi"; }
}
$object = new Object;
$object2 = $object();
echo $object2; // echos hi
That means that $object2 is equal to whatever that function returns.
Basically, you are calling a function, but using a variable as it's name. So:
function test(){ echo "hi"; }
$function_name = "test";
$function_name(); // echos hi.
In this case, you are just calling an object instead.
So, in reference to your question, this is actually not 'cloning' at all, unless the __invoke() function looks like this:
function __invoke(){ return this }
In which case, it would be a reference to the same class.
You are creating a second reference of the same object. Here is a proof:
<?php
class TestClass {
private $number;
function __construct($num) { $this->number = $num; }
function increment() { $this->number++; }
function __toString() { return (string) $this->number; }
}
$original = new TestClass(10);
echo "Testing =\n";
echo "--------------------------------\n";
echo '$equal = $original;' . "\n";
$equal = $original;
echo '$equal = ' . $equal . ";\n";
echo '$original->increment();' . "\n";
$original->increment();
echo '$equal = ' . $equal . ";\n";
echo "\n";
echo "Testing clone\n";
echo "--------------------------------\n";
echo '$clone = clone $original;' . "\n";
$clone = clone $original;
echo '$clone = ' . $clone . ";\n";
echo '$original->increment();' . "\n";
$original->increment();
echo '$clone = ' . $clone . ";\n";
Use clone if you want to create a copy of an instance.
Assuming that you mean
$object2 = $object;
And not
$object2 = $object();
PHP will create a reference to the original object, it will not copy it. See http://www.php.net/manual/en/language.oop5.basic.php, the section called
Object Assignment.
<?php
class Object{
public $value = 1;
public function inc(){
$this->value++;
}
}
$object = new Object;
$object2 = $object;
$object->inc();
echo $object2->value; // echos 2, proving it's by reference
I have abandoned all hope of ever being able to overload my constructors in PHP, so what I'd really like to know is why.
Is there even a reason for it? Does it create inherently bad code? Is it widely accepted language design to not allow it, or are other languages nicer than PHP?
You can't overload ANY method in PHP. If you want to be able to instantiate a PHP object while passing several different combinations of parameters, use the factory pattern with a private constructor.
For example:
public MyClass {
private function __construct() {
...
}
public static function makeNewWithParameterA($paramA) {
$obj = new MyClass();
// other initialization
return $obj;
}
public static function makeNewWithParametersBandC($paramB, $paramC) {
$obj = new MyClass();
// other initialization
return $obj;
}
}
$myObject = MyClass::makeNewWithParameterA("foo");
$anotherObject = MyClass::makeNewWithParametersBandC("bar", 3);
You can use variable arguments to produce the same effect. Without strong typing, it doesn't make much sense to add, given default arguments and all of the other "work arounds."
For completeness, I'll suggest Fluent Interfaces. The idea is that by adding return $this; to the end of your methods you can chain calls together. So instead of
$car1 = new Car('blue', 'RWD');
$car2 = new Car('Ford', '300hp');
(which simply wouldn't work), you can do:
$car = (new Car)
->setColor('blue')
->setMake('Ford')
->setDrive('FWD');
That way you can pick exactly which properties you want to set. In a lot of ways it's similar to passing in an array of options to your initial call:
$car = new Car(['make' => 'Ford', 'seats' => 5]);
PHP Manual: Function Arguments, Default Values
I have overcome this simply by using default values for function parameters. In __constuct, list the required parameters first. List the optional parameters after that in the general form $param = null.
class User
{
private $db;
private $userInput;
public function __construct(Database $db, array $userInput = null)
{
$this->db = $db;
$this->userInput = $userInput;
}
}
This can be instantiated as:
$user = new User($db)
or
$user = new User($db, $inputArray);
This is not a perfect solution, but I have made this work by separating parameters into absolutely mandatory parameters no matter when the object is constructed, and, as a group, optional parameters listed in order of importance.
It works.
True overloading is indeed unsupported in PHP. As #Pestilence mentioned, you can use variable arguments. Some people just use an Associative Array of various options to overcome this.
they say this work:
<?php
class A
{
function __construct()
{
$a = func_get_args();
$i = func_num_args();
if (method_exists($this,$f='__construct'.$i)) {
call_user_func_array(array($this,$f),$a);
}
}
function __construct1($a1)
{
echo('__construct with 1 param called: '.$a1.PHP_EOL);
}
function __construct2($a1,$a2)
{
echo('__construct with 2 params called: '.$a1.','.$a2.PHP_EOL);
}
function __construct3($a1,$a2,$a3)
{
echo('__construct with 3 params called: '.$a1.','.$a2.','.$a3.PHP_EOL);
}
}
$o = new A('sheep');
$o = new A('sheep','cat');
$o = new A('sheep','cat','dog');
// results:
// __construct with 1 param called: sheep
// __construct with 2 params called: sheep,cat
// __construct with 3 params called: sheep,cat,dog
?>
and, it seem every one are happy with it, but for me it didn't work...
if you get it to work, its one kind of overloading too...
it take all argoments and pass them to the secondary function constructor...
<?php
//php do not automatically call parent class constructor at all if child class has constructor so you have to call parent class constructor explicitly, however parent class constructor is called automatically if child class has no constructor
class MyClass
{
function construct1($value1)
{
echo "<br/> dummy constructor is called with 1 arguments and it is $value1";
}
function construct2($value1,$value2)
{
echo "<br/> dummy constructor is called with 2 arguments and it is $value1, $value2";
}
function construct3($value1,$value2,$value3)
{
echo "<br/> dummy constructor is called with 3 arguments and it is $value1, $value2 , $value3";
}
public function __construct()
{
$NoOfArguments = func_num_args(); //return no of arguments passed in function
$arguments = func_get_args();
echo "<br/> child constructor is called $NoOfArguments";
switch ($NoOfArguments) {
case 1:
self::construct1($arguments[0]);
break;
case 2:
self::construct2($arguments[0],$arguments[1]);
break;
case 3:
self::construct3($arguments[0],$arguments[1],$arguments[2]);
break;
default:
echo "Invalid No of arguments passed";
break;
}
}
}
$c = new MyClass();
$c2 = new MyClass("ankit");
$c2 = new MyClass("ankit","Jiya");
$c2 = new MyClass("ankit","Jiya","Kasish");
?>
You can use conditional statements in your constructor and then perform your task.
Eg.
class Example
{
function __construct($no_of_args)
{// lets assume 2
switch($no_of_args)
{
case 1:
// write your code
break;
case 2:
//write your 2nd set of code
break;
default:
//write your default statement
}
}
}
$object1 = new Example(1); // this will run your 1st case
$object2 = new Example(2); // this will run your 2nd case
and so on...
You can of course overload any function in PHP using __call() and __callStatic() magic methods.
It is a little bit tricky, but the implementation can do exactly what your are looking for.
Here is the resource on the official PHP.net website:
https://www.php.net/manual/en/language.oop5.overloading.php#object.call
And here is the example which works for both static and non-static methods:
class MethodTest
{
public function __call($name, $arguments)
{
// Note: value of $name is case sensitive.
echo "Calling object method '$name' "
. implode(', ', $arguments). "\n";
}
/** As of PHP 5.3.0 */
public static function __callStatic($name, $arguments)
{
// Note: value of $name is case sensitive.
echo "Calling static method '$name' "
. implode(', ', $arguments). "\n";
}
}
$obj = new MethodTest;
$obj->runTest('in object context');
MethodTest::runTest('in static context'); // As of PHP 5.3.0
And you can apply this to constructors by using the following code in the __construct():
$clsName = get_class($this);
$clsName->methodName($args);
Pretty easy.
And you may want to implement __clone() to make a clone copy of the class with the method that you called without having the function that you called in every instance...
Adding this answer for completeness with respect to current PHP , since later versions of PHP , you can in fact overload constructors in a way . Following code will help to understand ,
<?php
class A
{
function __construct()
{
$a = func_get_args();
$i = func_num_args();
if (method_exists($this,$f='__construct'.$i)) {
call_user_func_array(array($this,$f),$a);
}
}
function __construct1($a1)
{
echo('__construct with 1 param called: '.$a1.PHP_EOL);
}
function __construct2($a1,$a2)
{
echo('__construct with 2 params called: '.$a1.','.$a2.PHP_EOL);
}
function __construct3($a1,$a2,$a3)
{
echo('__construct with 3 params called: '.$a1.','.$a2.','.$a3.PHP_EOL);
}
}
$o = new A('sheep');
$o = new A('sheep','cat');
$o = new A('sheep','cat','dog');
?>
Output :
__construct with 1 param called: sheep
__construct with 2 params called: sheep,cat
__construct with 3 params called: sheep,cat,dog
In this case I recommend using Interfaces:
interface IExample {
public function someMethod();
}
class oneParamConstructor implements IExample {
public function __construct(private int $someNumber) {
}
public function someMethod(){
}
}
class twoParamConstructor implements IExample {
public function __construct(private int $someNumber, string $someString) {
}
public function someMethod(){
}
}
than in your code:
function doSomething(IExample $example) {
$example->someMethod();
}
$a = new oneParamConstructor(12);
$b = new twoParamConstructor(45, "foo");
doSomething($a)
doSomething($b)
As far as I know, constructor overloading in PHP is not allowed, simply because the developers of PHP did not include that functionality - this is one of the many complaints about PHP.
I've heard of tricks and workarounds, but true overloading in the OOP sense is missing. Maybe in future versions, it will be included.
I think we can also use constructor with default arguments as a potential substitute to constructor overloading in PHP.
Still, it is really sad that true constructor overloading is not supported in PHP.
<?php
class myClass {
public $param1 = 'a';
public $param2 = 'b';
public function __construct($param1 = NULL, $param2 = NULL) {
if ($param1 == NULL && $param2 == NULL) {
// $this->param1 = $param1;
// $this->param2 = $param2;
} elseif ($param1 == NULL && $param2 !== NULL) {
// $this->param1 = $param1;
$this->param2 = $param2;
} elseif ($param1 !== NULL && $param2 == NULL) {
$this->param1 = $param1;
// $this->param2 = $param2;
} else {
$this->param1 = $param1;
$this->param2 = $param2;
}
}
}
// $myObject = new myClass();
// $myObject = new myClass(NULL, 2);
$myObject = new myClass(1, '');
// $myObject = new myClass(1, 2);
echo $myObject->param1;
echo "<br />";
echo $myObject->param2;
?>
public function construct1($user , $company)
{
dd("constructor 1");
$this->user = $user;
$this->company = $company;
}
public function construct2($cc_mail , $bcc_mail , $mail_data,$user,$company)
{
dd('constructor 2');
$this->mail_data=$mail_data;
$this->user=$user;
$this->company=$company;
$this->cc_mail=$cc_mail;
$this->bcc_mail=$bcc_mail;
}
public function __construct()
{
$NoOfArguments = func_num_args(); //return no of arguments passed in function
$arguments = func_get_args();
switch ($NoOfArguments) {
case 1:
self::construct1($arguments[0]);
break;
case 5:
self::construct2($arguments[0],$arguments[1],$arguments[2],$arguments[3],$arguments[4]);
break;
default:
echo "Invalid No of arguments passed";
break;
}
I'm really no OOP expert, but as I understand it overloading means the ability of a method to act differently depending in the parameters it receives as input. This is very much possible with PHP, you just don't declare the input types since PHP does not have strong typing, and all the overloading is done at runtime instead of compile time.