$this¶
$this is a variable that represents the current object instance. Its value is different for each object, and remains the same throughout every non-static method call made on that object.
$this is also called a pseudo-variable. It is never explicitly set, but is available as soon as a non-static method starts. It is also never available, nor can even be created, outside a method.
$this cannot be unset, nor assigned a different value than the current object. This means it cannot be used as the name of a function or method parameter, as a global variable global $this;, or as an explicit lexical variable in a closure use ($this).
Closures and arrow functions defined inside a non-static method automatically have access to $this, without needing to import it with use. A closure declared with the static keyword has no access to $this. A named function declared inside a method, on the other hand, is not a closure, and does not have access to $this either.
$this is not available in static methods, as they do not require an object to be invoked.
When a non-static method is invoked with the :: syntax from another method of a related class, for example parent::method() or self::method(), $this still refers to the calling object.
In a trait, $this refers to the object of the class that uses the trait, not to the trait itself.
$this may use the array syntax, if the underlying class supports the ArrayAccess interface.
There is no special variable called $that.
<?php
class X {
private $y = 1;
function foo() {
return $this->y;
}
}
?>
See also PHP $this and What is $this?.
Related : Class, Trait, $php_errormsg, Arrow Functions, get_class(), Closure, Closure Binding, Static Method, Scope Resolution Operator ::, Pseudo-variable
