I want to declare a variable inside a class with an unknown name
class Example {
function newVar($name, $value) {
$this->$name = $value;
}
}
And I want to use it that way
$c = new Example();
$c->newVar('MyVariableName', "This is my Value");
echo($c->MyVariableName);
The Important thing is, that I do not know the name of the variable. So I cannot put a public $MyVariable inside the class.
Is that in anyway possible? and if yes, can i do this with different scopes (private, protected, public) ?
U should use magic methods __get and __set (example without checking):
class Example {
private $data = [];
function newVar($name, $value) {
$this->data[$name] = $value;
}
public function __get($property) {
return $this->data[$property];
}
public function __set($property, $value) {
$this->data[$property] = $value;
}
}
$c = new Example();
$c->newVar('MyVariableName', "This is my Value");
echo($c->MyVariableName);
// This is my Value
$c->MyVariableName = "New value";
echo($c->MyVariableName);
// New value
See http://php.net/manual/en/language.oop5.magic.php
If i am understanding this correctly you can tweak a little bit by using key value array
class Example {
private $temp;
function __construct(){
$this->temp = array();
}
function newVar($name, $value) {
$this->temp[$name] = $value;
}
function getVar($name){
return $this->temp[$name];
}
}
$c = new Example();
$c->newVar('MyVariableName', "This is my Value");
echo($c->getVar('MyVariableName'));
Instead of using private you can use protected as well.
Your looking for magic calling. In PHP you can use the __call() function to do stuff like that. Have a look here: http://www.garfieldtech.com/blog/magical-php-call
Off the top of my head, something like
function __call($vari, $args){
if(isset($this->$vari){
$return = $this->$vari;
}else{
$return = "Nothing set with that name";
}
}
This will also work for private, protected and public. Can also use it to call methods as required in a class
Related
Is there a function like this so I can do:
populate_array($array, 'key', $value)
instead of doing:
$array['key'] = $value;
?
I'm asking this because I want to circumvent the "Indirect modification of overloaded property" error that occurs when you use magic getter and setter and you want to set an array attribute:
class MyClass
{
private $string;
private $array;
public function __set($attribute, $value)
{
$this->$attribute = $value;
}
public function __get($attribute)
{
if (isset($attribute))
{
return $this->$attribute;
}
}
}
$obg = new MyClass();
$obg->string = 'Hey it works!';
$obg->array = ['This works', 'too!'];
$obg->array['key'] = 'This will throw `Indirect modification of overloaded property MyClass::$array has no effect`';
I would add a method to your class:
class MyClass
{
private $string;
private $array;
/* snip */
public function addItem($key, $value){
$this->array[$key] = $value;
}
}
This will allow you to set from outside the class:
$obg = new MyClass();
$obg->addItem('someKey','someValue');//Assumes array already exists.
I would recommend you to create a public method to modify an internal variable inside the class. This is the way it should be done. (principle of encapsulation)
class MyClass
{
private $string;
private $array;
public function setArrayAtKey($key, $value){
$this->array[$key] = $value;
}
}
And calling it like:
$obg = new MyClass();
$obg->setArrayAtKey('key', 'this works');
This should be the correct code in your case:
class MyClass
{
}
$obg = new MyClass();
$obg->string = 'Hey it works!';
$obg->array = ['This works', 'too!'];
$obg->array['key'] = 'This will NOT throw `Indirect modification...';
But if you have good reasons to use magic __get and __set with private properties, then make your array property an object that implements ArrayAccess, or just use the ArrayObject class:
$obg->array = new ArrayObject(['This works', 'too!']);
$obg->array['key'] = 'This will NOT throw `Indirect modification...';
You can create custom one.
function setArrayValue(&$array, $key, $value)
{
$array[$key] = $value;
}
As per your second update -
class MyClass
{
private $arr1;
private $arr2;
public function setArrayValue($arrayName, $key, $value)
{
$this->$arrayName[$key] = $value;
}
}
$obg = new MyClass();
$obg->setArrayValue('arr1', 2, 3);
$obg->setArrayValue('arr3', 6, 9);
There could be many methods, it depends on your need.
I was wondering if you could get the class name and property name from a property reference in PHP?
class Test {
public static $TestProp;
}
GetDoc(& Test::$TestProp);
function GetDoc($prop) {
$className = getClassName($prop);
$propertyName = getPropertyName($prop);
}
what I'm looking for is if it is possible to create the functions getClassName and getPropertyName?
What you want is basically not possible; a property doesn't know its parent structure.
The only sane thing I could think of is to use reflection for it:
class Test
{
public static $TestProp = '123';
}
//GetDoc(& Test::$TestProp);
GetDoc('Test', 'TestProp');
function GetDoc($className, $propName)
{
$rc = new ReflectionClass($className);
$propValue = $rc->getStaticPropertyValue($propName);
}
Within the Test class you could use __CLASS__ as a convenient reference for the class name.
I have figured out the way to get this to work there is a lot of magic that goes on just to get this to work, but in my case it's worth it.
class Test {
private $props = array();
function __get($name) {
return new Property(get_called_class(), $name, $this->props[$name]);
}
function __set($name, $value) {
$props[$name] = $value;
}
}
class Property {
public $name;
public $class;
public $value;
function __construct($class, $name, $value) {
$this->name = $name;
$this->class = $class;
$this->value = $value;
}
function __toString() {
return $value.'';
}
}
function GetClassByProperty($prop) {
return $prop->class.'->'.$prop->name;
}
$t = new Test();
$t->Name = "Test";
echo GetClassByProperty($t->Name);
this example yes I know it's complex, but it does the job how I'd want it to, will print out "Test->Name" I can also get the value by saying $prop->value. If I want to compare the value to another object I can simply do this:
if($t->Name == "Test") { echo "It worked!!"; }
hope this isn't too confusing but it was a fun exploration into PHP.
Php have a build in function called get_class
i have something like this:
class foo
{
//code
}
$var = new foo();
$var->newVariable = 1; // create foo->newVariable
$var->otherVariable = "hello, im a variable"; //create foo->otherVariable
i can get in class foo a list of all variables defined outside by user (newVariable, otherVariable,etc)? Like this:
class foo
{
public function getUserDefined()
{
// code
}
}
$var = new foo();
$var->newVariable = 1; // create foo->newVariable
$var->otherVariable = "hello, im a variable"; //create foo->otherVariable
var_dump($var->getUserDefined()); // returns array ("newVariable","otherVariable");
Thanks!.
Yes, using get_object_vars() and get_class_vars():
class A {
var $hello = 'world';
}
$a = new A();
$a->another = 'variable';
echo var_dump(get_object_vars($a));
echo '<hr />';
// Then, you can strip off default properties using get_class_vars('A');
$b = get_object_vars($a);
$c = get_class_vars('A');
foreach ($b as $key => $value) {
if (!array_key_exists($key,$c)) echo $key . ' => ' . $value . '<br />';
}
What is your goal? Imo it's not very good practice (unless you really know what you are doing). Maybe it's good idea consider create some class property like "$parameters" and then create setter and getter for this and use it in this way:
class foo {
private $variables;
public function addVariable($key, $value) {
$this->variables[$key] = $value;
}
public function getVariable($key) {
return $this->variables[$key];
}
public function hasVariable($key) {
return isset($this->variables[$key]);
}
(...)
}
$var = new foo();
$var->addVariable('newVariable', 1);
$var->addVariable('otherVariable', "hello, im a variable");
And then you can use it whatever you want, for example get defined variable:
$var->getVariable('otherVariable');
To check if some var is already defined:
$var->hasVariable('someVariable')
get_class_vars() http://php.net/manual/en/function.get-class-vars.php
You question is not clear though.
$var->newVariable = 1;
there are two possible contex of above expression
1) you are accessing class public variables.
like
class foo
{
public $foo;
public function method()
{
//code
}
}
$obj_foo = new foo();
$obj_foo->foo = 'class variable';
OR
2) you are defining class variable runtime using _get and _set
class foo
{
public $foo;
public $array = array();
public function method()
{
//code
}
public function __get()
{
//some code
}
public function __set()
{
// some code
}
}
$obj_foo = new foo();
$obj_foo->bar= 'define class variable outside the class';
so in which context your question is talking about?
I'm wondering if it's possible, and in case it is, how shoud I achive that:
$this->id <-- i have such thing. but to make it more usable i'd like to have $this->(and here to change the values)
for ex: I might have $this->id $this->allID $this->proj_id
how can I make so that actually I have $this->($myvariable here, that has a unique name in it)?
You can simply use this:
$variable = 'id';
if ( isset ( $this->{$variable} ) )
{
echo $this->{$variable};
}
Here is the solution : http://www.php.net/manual/en/language.oop5.overloading.php#language.oop5.overloading.members
An example of using it is here :
class myClass {
/** Location for overloaded data. */
private $myProperties = array();
public function __set($name, $value)
{
$this->myProperties[$name] = $value;
}
public function __get($name)
{
if (array_key_exists($name, $this->myProperties))
{
return $this->data[$name];
}
}
}
You should check out the variable variables manual on the PHP site.
With that, it could look like:
<?php
echo ${'this->'.$yourvariable};
?>
I prefer to use call_user_func and pass the parameters as array instead.
public function dynamicGetterExample()
{
$property = 'name'; // as an example...
$getter = 'get'.ucfirst($property);
$value = call_user_func(array($this,$getter));
if (empty($value)) {
throw new \Exception('Required value is empty for property '.$property);
}
return $value;
}
How can i perform a function once a variable's value has been set?
say like
$obj = new object(); // dont perform $obj->my_function() just yet
$obj->my_var = 67 // $obj->my_function() now gets run
I want the object to do this function and now having to be called by the script.
Thanks
EDIT
my_var is predefined in the class, __set is not working for me.
Use a private property so __set() is invoked:
class Myclass {
private $my_var;
private $my_var_set = false;
public function __set($var, $value) {
if ($var == 'my_var' && !$this->my_var_set) {
// call some function
$this->my_var_set = true;
}
$this->$var = $value;
}
public function __get($var, $value) {
return $this->$name;
}
}
See Overloading. __set() is called because $my_var is inaccessible and there is your hook.
I'd recommend to create a setter function for $obj and include the relevant function call there. So basically your code would look somehow like this:
$obj = new ClassOfYours();
$obj->setThatValue("apple");
Of course you would have to take care that all assignments to ThatValue need to be
done through that setter in order make it work properly. Assuming that you're on php5 I'd set that property to private, so all direct assignments will cause an runtime error.
A good overview about OOP in php can be found in this article on devarticles.com.
HTH
To acheive exactly what you describe, you'd have to use a magic setter.
class ObjectWithSetter {
var $data = array();
public function my_function() {
echo "FOO";
}
public function __set($name, $value) {
$this->data[$name] = $value;
if($name == 'my_var') {
$this->my_function();
}
}
public function __get($name) {
if (array_key_exists($name, $this->data)) {
return $this->data[$name];
}
$trace = debug_backtrace();
trigger_error(
'Undefined property via __get(): ' . $name .
' in ' . $trace[0]['file'] .
' on line ' . $trace[0]['line'],
E_USER_NOTICE);
return null;
}
/** As of PHP 5.1.0 */
public function __isset($name) {
return isset($this->data[$name]);
}
public function __unset($name) {
unset($this->data[$name]);
}
}
Assuming you want to call my_function() once you set a value, that case you can encapsulate both the operations into one. Something like you create a new function set_my_var(value)
function set_my_var(varvalue)
{
$this->my_var = varvalue;
$this->my_function();
}