<?php
class Popular
{
public static function getVideo()
{
return $this->parsing();
}
}
class Video
extends Popular
{
public static function parsing()
{
return 'trololo';
}
public static function block()
{
return parent::getVideo();
}
}
echo Video::block();
I should definitely call the class this way:
Video::block();
and not initialize it
$video = new Video();
echo $video->block()
Not this!
Video::block(); // Only this way <<
But:
Fatal error: Using $this when not in object context in myFile.php on line 6
How to call function "parsing" from the "Popular" Class?
Soooooooory for bad english
As your using a static method, you cant use $thiskeyword as that can only be used within objects, not classes.
When you use the new keyword, your creating and object from a class, if you have not used the new Keyword then $this would not be available as its not an Object
For your code to work, being static you would have to use the static keyowrd along with Scope Resolution Operator (::) as your method is within a parent class and its its not bounded, Use the static keyword to call the parent static method.
Example:
class Popular
{
public static function getVideo()
{
return static::parsing(); //Here
}
}
What does $this mean in PHP?
paamayim-nekudotayim - Scope Resolution
http://php.net/manual/en/language.oop5.static.php
change return $this->parsing(); to return self::parsing();
Related
I currently am using PHP and was reading the PHP manual but still have a problem with $this.
Is $this something global or is it is just another variable name to build objects on?
Here is an example:
public function using_a_function($variable1, $variable2, $variable3)
{
$params = array(
'associative1' => $variable1,
'associative2' => $variable2,
'associative3' => $variable3
);
$params['associative4'] = $this->get_function1($params);
return $this->get_function2($params);
}
How would $this work for the return function? I guess I am confused on how this function builds. I understand building the associate array part with a name being a valuekey names => value, but $this throws me off on this example.
$this is only used in object oriented programming (OOP) and refers to the current object.
class SomeObject{
public function returnThis(){
return $this;
}
}
$object = new SomeObject();
var_dump($object === $object->returnThis()); // true
This is used inside the object to reach member variables and methods.
class SomeOtherClass{
private $variable;
public function publicMethod(){
$this->variable;
$this->privateMethod();
}
private function privateMethod(){
//
}
}
It is refered to as the Object scope, lets use an example class.
Class Example
{
private $property;
public function A($foo)
{
$this->property = $foo;
// we are telling the method to look at the object scope not the method scope
}
public function B()
{
return self::property; // self:: is the same as $this
}
}
We can now instance our object and use it in another way also:
$e = new Example;
$e::A('some text');
// would do the same as
$e->A('some other text');
This is just a way of accessing the scope of the Object because methods cannot access other method scopes.
You can also extend a class and use the parent:: to call the class extension scope, for example:
Class Db extends PDO
{
public function __construct()
{
parent::__construct(....
Which would access the PDO construct method rather than its own construct method.
In your case, the method is calling other methods that are in the object. Which can be called using $this-> or self::
Trying to get some data from one method in side static method(using it inside a other class) but I get the 'Using $this when not in object context in...' error.
Below a basic example
class mClass{
public $someVar = 'Hello world...';
public function passFunc(){
$give = $this->someVar;
return $give;
}
public static function showFunc(){
$show = self::passFunc();
return $show;
}
}
mClass::showFunc();// show error: Using $this when not in object context in...
You can't use $this, when you are working with static variables. $this is a pointer to the current object, but static variables belongs to class.
A class method (or static function) isn't tied to a particular instance of your class, i.e. it doesn't have $this although self is available.
A class method can access static properties or methods, but accessing anything else within the class will raise an error. It's best to look at static methods as a means to organize functions; as such, they operate in between external functions and instance methods.
In your case, you'd have to create an instance inside your static method:
public static function showFunc()
{
$o = new self;
$show = $o->passFunc();
return $show;
}
Due to the fact that you can not use $this-> inside a static functio, how are you supposed to access regular functions inside a static?
private function hey()
{
return 'hello';
}
public final static function get()
{
return $this->hey();
}
This throws an error, because you can't use $this-> inside a static.
private function hey()
{
return 'hello';
}
public final static function get()
{
return self::hey();
}
This throws the following error:
Non-static method Vote::get() should not be called statically
How can you access regular methods inside a static method? In the same class*
Static methods can only invoke other static methods in a class. If you want to access a non-static member, then the method itself must be non-static.
Alternatively, you could pass in an object instance into the static method and access its members. As the static method is declared in the same class as the static members you're interested in, it should still work because of how visibility works in PHP
class Foo {
private function bar () {
return get_class ($this);
}
static public function baz (Foo $quux) {
return $quux -> bar ();
}
}
Do note though, that just because you can do this, it's questionable whether you should. This kind of code breaks good object-oriented programming practice.
You can either provide a reference to an instance to the static method:
class My {
protected myProtected() {
// do something
}
public myPublic() {
// do something
}
public static myStatic(My $obj) {
$obj->myProtected(); // can access protected/private members
$obj->myPublic();
}
}
$something = new My;
// A static method call:
My::myStatic($something);
// A member function call:
$something->myPublic();
As shown above, static methods can access private and protected members (properties and methods) on objects of the class they are a member of.
Alternatively you can use the singleton pattern (evaluate this option) if you only ever need one instance.
I solved this by creating an object of the concerning class inside a static method. This way i can expose some specific public functions as static function as well. Other public functions can only be used like $object->public_function();
A small code example:
class Person
{
public static function sayHi()
{
return (new Person())->saySomething("hi");
}
public function saySomething($text)
{
echo($text);
}
private function smile()
{
# dome some smile logic
}
}
This way you can only say hi if using the static function but you can also say other things when creating an object like $peter->saySomething('hi');.
Public functions can also use the private functions this way.
Note that i'm not sure if this is best practice but it works in my situation where i want to be able to generate a token without creating an object by hand each time.
I can for example simply issue or verify a token string like TokenManager::getTokenToken(); or TokenManager::verifyToken("TokenHere"); but i can also issue a token object like $manager = new TokenGenerator(); so i can use functionality as $manager->createToken();, $manager->updateToken(updateObjectHere); or $manager->storeToken();
how do i call a static method from another method inside the same class?
$this->staticMethod();
or
$this::staticMethod();
self::staticMethod();
More information about the Static keyword.
Let's assume this is your class:
class Test
{
private $baz = 1;
public function foo() { ... }
public function bar()
{
printf("baz = %d\n", $this->baz);
}
public static function staticMethod() { echo "static method\n"; }
}
From within the foo() method, let's look at the different options:
$this->staticMethod();
So that calls staticMethod() as an instance method, right? It does not. This is because the method is declared as public static the interpreter will call it as a static method, so it will work as expected. It could be argued that doing so makes it less obvious from the code that a static method call is taking place.
$this::staticMethod();
Since PHP 5.3 you can use $var::method() to mean <class-of-$var>::; this is quite convenient, though the above use-case is still quite unconventional. So that brings us to the most common way of calling a static method:
self::staticMethod();
Now, before you start thinking that the :: is the static call operator, let me give you another example:
self::bar();
This will print baz = 1, which means that $this->bar() and self::bar() do exactly the same thing; that's because :: is just a scope resolution operator. It's there to make parent::, self:: and static:: work and give you access to static variables; how a method is called depends on its signature and how the caller was called.
To see all of this in action, see this 3v4l.org output.
This is a very late response, but adds some detail on the previous answers
When it comes to calling static methods in PHP from another static method on the same class, it is important to differentiate between self and the class name.
Take for instance this code:
class static_test_class {
public static function test() {
echo "Original class\n";
}
public static function run($use_self) {
if($use_self) {
self::test();
} else {
$class = get_called_class();
$class::test();
}
}
}
class extended_static_test_class extends static_test_class {
public static function test() {
echo "Extended class\n";
}
}
extended_static_test_class::run(true);
extended_static_test_class::run(false);
The output of this code is:
Original class
Extended class
This is because self refers to the class the code is in, rather than the class of the code it is being called from.
If you want to use a method defined on a class which inherits the original class, you need to use something like:
$class = get_called_class();
$class::function_name();
In the later PHP version self::staticMethod(); also will not work. It will throw the strict standard error.
In this case, we can create object of same class and call by object
here is the example
class Foo {
public function fun1() {
echo 'non-static';
}
public static function fun2() {
echo (new self)->fun1();
}
}
call a static method inside a class
className::staticFunctionName
example
ClassName::staticMethod();
I have a question regarding static function in php.
let's assume that I have a class
class test {
public function sayHi() {
echo 'hi';
}
}
if I do test::sayHi(); it works without a problem.
class test {
public static function sayHi() {
echo 'hi';
}
}
test::sayHi(); works as well.
What are the differences between first class and second class?
What is special about a static function?
In the first class, sayHi() is actually an instance method which you are calling as a static method and you get away with it because sayHi() never refers to $this.
Static functions are associated with the class, not an instance of the class. As such, $this is not available from a static context ($this isn't pointing to any object).
Simply, static functions function independently of the class where they belong.
$this means, this is an object of this class. It does not apply to static functions.
class test {
public function sayHi($hi = "Hi") {
$this->hi = $hi;
return $this->hi;
}
}
class test1 {
public static function sayHi($hi) {
$hi = "Hi";
return $hi;
}
}
// Test
$mytest = new test();
print $mytest->sayHi('hello'); // returns 'hello'
print test1::sayHi('hello'); // returns 'Hi'
Entire difference is, you don't get $this supplied inside the static function. If you try to use $this, you'll get a Fatal error: Using $this when not in object context.
Well, okay, one other difference: an E_STRICT warning is generated by your first example.
Calling non-static methods statically generates an E_STRICT level warning.
In a nutshell, you don't have the object as $this in the second case, as
the static method is a function/method of the class not the object instance.
After trying examples (PHP 5.3.5), I found that in both cases of defining functions you can't use $this operator to work on class functions. So I couldn't find a difference in them yet. :(