What I'm trying to do is bitwise flagging when using setPARAM().
What I know is magic function __get() or __set() being called when you refering protected variables and its also not a good practice.
So,
// This is an example for what I did.
class boo {
// #var string name ;
public $name;
// #var int edit ;
public $edit;
public function setName($var=null) {
.. do stuff..
}
}
Every time when I add an property, class requires additional get, set function. Can I handle this differently except using __set()?
Related
Say I have a very simple CRUD system in PHP to manage a database. Say it holds a list of products. Using Doctrine ORM, I'd like to query the database and view/edit/add records. According to the Getting Started manual,
When creating entity classes, all of the fields should be protected or
private (not public), with getter and setter methods for each one
(except $id). The use of mutators allows Doctrine to hook into calls
which manipulate the entities in ways that it could not if you just
directly set the values with entity#field = foo;
This is the sample provided:
// src/Product.php
class Product
{
/**
* #var int
*/
protected $id;
/**
* #var string
*/
protected $name;
public function getId()
{
return $this->id;
}
public function getName()
{
return $this->name;
}
public function setName($name)
{
$this->name = $name;
}
}
// Recording a new title
$product->setName("My new name");
$db->persist($product);
$db->flush();
// Echoing the title
echo $product->getName();
However, this seems overly complicated. Say I don't have a need to hook into calls to manipulate entities, as explained in the manual. I can make this code much shorter and do this:
// src/Product.php
class Product
{
/**
* #var int
*/
public $id;
/**
* #var string
*/
public $name;
}
This would allow things like this:
$product = $db->getRepository('Product')->find(1);
// Recording a new name
$product->name = "My new title";
$db->persist($product);
$db->flush();
// Echoing the title
echo $product->name;
The advantages are:
Always using the exact same name
No extra setters and getters in the entity class
What is the disadvantage of using this? Am I taking certain risks here?
Say I don't have a need to hook into calls to manipulate entities, as explained in the manual.
You do not need to hook into these calls, but Doctrine does. Doctrine internally overrides these getters and setters to implement an ORM as transparently as possible.
Yes, it is overly complicated, but that is the PHP language at fault and not Doctrine. There is nothing inherently wrong with using public properties, it is just that the PHP language does not allow creating custom getters/setters the way some other languages do (such as Kotlin, C#).
What does Doctrine do exactly? It generates so-called Proxy objects to implement lazy loading. These objects extend your class and override certain methods.
For your code:
// src/Product.php
class Product
{
/**
* #var int
*/
protected $id;
/**
* #var string
*/
protected $name;
public function getId()
{
return $this->id;
}
public function getName()
{
return $this->name;
}
public function setName($name)
{
$this->name = $name;
}
}
Doctrine might generate:
class Product extends \YourNamespace\Product implements \Doctrine\ORM\Proxy\Proxy
{
// ... Lots of generated methods ...
public function getId(): int
{
if ($this->__isInitialized__ === false) {
return (int) parent::getId();
}
$this->__initializer__ && $this->__initializer__->__invoke($this, 'getId', []);
return parent::getId();
}
public function getName(): string
{
$this->__initializer__ && $this->__initializer__->__invoke($this, 'getName', []);
return parent::getName();
}
// ... More generated methods ...
}
(What this does exactly is not the point, the point is that Doctrine MUST be able to override getters and setters to implement an ORM)
To see for yourself, inspect the generated Proxy objects in the proxy directory of Doctrine. See the Advanced Configuration section for more info on configuring the proxy directory. Also see Working with Objects for more info on Proxy objects and how Doctrine utilizes them.
Why not use public entity classes in Doctrine?
Actually what you are asking is:
Where does this getters/setters come from?
It comes from the Encapsulation in OOP.
so, what is encapsulation?
It’s the way we define the visibility of our properties and methods. When you’re creating classes, you have to ask yourself what properties and methods can be accessed outside of the class.
Let’s say we had a property named id. If a class extends your class, is it allowed to manipulate and access id directly? What if someone creates an instances of your class? Are they allowed to manipulate and access id?
NO! They should not be able to reach the id attribute directly.
Why not?
Example: What happens if you only accept Invoice Ids which start with "IX" and other classes have access to your class and they set the invoice_id directly?
What happens if they accidentally set the invoice_id to "XX12345"?
of course, you cannot do anything (like validating the input), because you are using public properties and no setters.
but if you had a setter method in your class, you could just do
private $invoiceId;
public function setInvoiceId($invoiceId)
{
if (is_null($invoiceId) || preg_match("#^IX(.*)$#i", $invoiceId) === 0)
return false;
$this->invoiceId = $invoiceId;
return $this;
}
I hope it was clear enought. I will try to extend the answer
Here is my code:
class {
$property = "something";
public static function myfunc() {
return $this->property;
}
}
but PHP throws this:
Using $this when not in object context
I know, the problem is using $this-> in a static method, ok I remove it like this:
class {
$property = "something";
public static function myfunc() {
return self::property;
}
}
But sadly PHP throws this:
Undefined class constant 'property'
How can I access a property which is out of a static method in it?
Generally, you should not do it. Static methods don't have an access to instance fields for a reason. You can do something like this, though:
// define a static variable
private static $instance;
// somewhere in the constructor probably
self::$instance = $this;
// somewhere in your static method
self::$instance->methodToCall();
Note that it will work only for a single instance of your class, since static variables are shared between all instances (if any).
You'll also need to add a bunch of validations (e.g. is $instance null?) and pay attention to all the implementation details that may cause you some troubles.
Anyway, I don't recommend this approach. Use it at your own risk.
Explaination
If you want to use a variable that wont change inside a class you don't want to instanciate, you need to use the static keyword in order to access it later in a method.
Also, you need a name for your class.
And finally, if you didn't specify a keyword as protected or public, you variable may be accessible outside the word, and so the method would be pointless. So I assume you need a protected value in order to use the method to call that variable.
Source-code
class Foo {
protected static $property = 'something';
public function getProperty() {
return self::$property;
}
}
echo Foo::getProperty(); /* will display : something */
echo Foo::$property; /* change from protected to public to use that syntax */
Documentation
PHP : classes.
PHP : static.
PHP : visibility.
I have an ActiveRecord class where I need to have some kind of dynamic variables in it.
The dynamic variable should be created for each existing variable. For example if I have a variable $test in my class, then it should also has $testDyn.
Example:
class User extends ActiveRecord
{
public $name;
public $age;
public $address;
/**
* dynamic vars
*/
public $nameDyn;
public $ageDyn;
public $addressDyn;
public function tableName()
{
return 'user';
}
...
}
There are ActiveRecords which have many variables and it would not be the best idea to do and manually create those dynamic vars for each variables. Are there any easy way / behavior which can do this?
You can create custom behavior for these purposes and attach for every needed model.
As for properties, you can explicitly specify it via parameter through behavior config, or use something like this:
$reflect = new ReflectionClass(new YourClass());
$props = $reflect->getProperties(ReflectionProperty::IS_PUBLIC);
More info and examples are available here.
You can additionally use some naming convention.
For dynamic properties you can override __get() magic method in behavior. See here.
Yii2 example (taken from yii2tech/ar-linkmany behavior by Paul Klimov, one of the framework contributors):
/**
* PHP getter magic method.
* This method is overridden so that relation attribute can be accessed like property.
*
* #param string $name property name
* #throws UnknownPropertyException if the property is not defined
* #return mixed property value
*/
public function __get($name)
{
try {
return parent::__get($name);
} catch (UnknownPropertyException $exception) {
if ($name === $this->relationReferenceAttribute) {
return $this->getRelationReferenceAttributeValue();
}
throw $exception;
}
}
To understand more about behaviors concept, please refer to according official docs section Behaviors.
Is it normal to not defined variable in class properties, but indicate at once in constructor ?
I just learn OOP, and found that example:
class Foo {
public function __construct($name) {
$this->_name = $name;
}
}
and it works, i can use this variable
$objFoo = new Foo('Fido');
echo $objFoo->_name; //output 'Fido'
But in class properties, there has no defined variable $_name, like public $_name in start of class.
So if we dont define it directly, it will be created automatically throught constructor ? And is it real to set scope for variable that way, protected, private ?
In PHP, this is called "object overloading", you can add/set new properties on (almost) any instance on the fly. However, you shouldn't do this. These properties make your code more error prone, less maintainable and overloaded properties that are added are slower: details here.
Pre-declaring properties allows for better documentation, your IDE's auto-completion function is actually worth something then, and you don't get in the habit of relying on something that doesn't always work. I tend to write my data models along these lines:
class DataModel
{
/**
* #var int
*/
protected $id = null;
/**
* #var string
*/
protected $name = null;
/**
* #var \DateTime
*/
protected $birthday = null;
public function __construct(array $data)
{}//set values
public function __set($name, $value)
{
throw new \BadMethodCallException('Do not attempt overloading, use getters and setter');
}
}
I define getters and setters for all of the properties, to ensure type safety, and validation can be done. I expressly disable overloading because of the risk of typo's, and difficult debugging. I often find myself disabling __sleep, __serialize and all those magic methods for pretty much the same reason.
Creating object members on the fly, meaning just assigning a value to it without declaring the member, is not limited to the constructor method. It can be done from inside of every method in the class or even from outside of the class, like this:
$c = new stdClass();
$c->foo = "bar";
While there are still a few use cases for this, I suggest to declare every class member explicitly in the head of the class. Also you will want in most cases to declare class members as protected or even private which requires an explicit declaration anyway.
I'm querying for the ID of a field by accessing a class function which someone has already put in place. The result is a object returned with protected member variables. I'm struggling to see how I can access the member variable values outside the class.
Accessing protected or private variables from public is incorrect (thats why they are protected or private). So better is to extend class and access required property or make getter method to get it publicaly. But if you still want to get properties without extending and if you are using PHP 5, you can acces with Reflection classes. Actually try ReflectionProperty class.
class Foo { protected $bar; }
$foo = new Foo();
$rp = new ReflectionProperty('Foo', 'bar');
$rp->setAccessible(true);
echo $rp->getValue($foo);
Here is the correct answer:
We can use bind() or bindTo methods of Closure class to access private/protected data of some class, for example:
class MyClass {
protected $variable = 'I am protected variable!';
}
$closure = function() {
return $this->variable;
};
$result = Closure::bind($closure, new MyClass(), 'MyClass');
echo $result(); // I am protected variable!
Just add a "get" method to the class.
class Foo
{
protected $bar = 'Hello World!';
public function getBar()
{
return $this->bar;
}
}
$baz = new Foo();
echo $baz->getBar();
I'm struggling to see how I can access the member variable values outside the class.
You can't: That's the whole point of protected.
You would have to extend the class with a method that fetches the variables for you.
You can't do this on an instantiated object, though - you would have to influence either the class definition, or change the class of the object at the point it was created.
You can access the protected member of class out side the class, also without extending protected member class, also without using any function of protected member class. Use below function to access it.
function getProtectedMember($class_object,$protected_member) {
$array = (array)$class_object; //Object typecast into (associative) array
$prefix = chr(0).’*’.chr(0); //Prefix which is prefixed to protected member
return $array[$prefix.$protected_member];
}
Please visit the Link to check more details about it.
with closure acces php protected variable for example
class ForExample
{
protected $var=122;
}
$call=function(){
echo $this->var;
};
$call->call(new ForExample());
If you really need that value:
Modify the class and add a public method that returns the value you want.
If you can't modify it, consider extending it and exposing the value there (it will be accessible, since it's protected). Prefer the first option, this is more of a hack.
Clearly, the class designer did not think you'd need the value you're trying to access, otherwise he would have added a method to retrieve it himself. Therefore, reconsider what you're doing.
DISCLAIMER: I don't remember how to code. It's been "a while". This may be completely off.
Well, first of all, if the members are protected, the original designer didn't intend for you to access them directly. Did you check for accessor methods?
If there aren't any, and you're conviced you really need these protected members, you could extend the type with accessors, cast, and get them that way. Like (in C++-like code)
class MyClass : public OldClass
{
public:
int getSomeValue() { return protectedValue; }
void setSomeValue(int value) { protectedValue=value; }
char* getOtherValue() { return otherProtectedValue; }
}
and then to use it
MyClass* blah = (MyClass*)TheirFactory->GiveMeAClass();
int yay=blah->getSomeValue();
You get the drift. Hope this works for you, Internet Explorer makes for a lousy compiler, so I haven't been able to test it.
}