PHP
protected access
Learn that protected access is limited to the class and its subclasses.
protected access, in the visibility context
You saw the protected modifier briefly in the inheritance lesson. Now let's look at it more closely in the visibility context.
When a property or method is protected, it can only be accessed from:
- inside the class that declares it
- subclasses that
extends this class - parent classes in the same hierarchy
Direct access from outside is not possible: writing $obj->protectedProp triggers a fatal error. So protected is ideal for data you want to hide from the outside but expose to subclasses.
protected cannot be reached from outside
Consider this example: class Animal { protected string $name; }. Here $name is protected. From outside the class, writing $cat->name triggers a fatal error: Cannot access protected property.
But if you write Dog extends Animal and inside Dog you access $this->name, it works. Because Dog is a subclass of Animal, it can use protected members.
In other words, protected is closed to the outside world but open to subclasses through inheritance. This lets subclasses reuse the parent's internal state.
Exercise Subclass with a protected property
Define an Animal class with a protected string $name property and a __construct(string $name) that assigns $this->name = $name. Then declare Dog extends Animal with a public function getName(): string method that does return $this->name. Finally create $dog = new Dog("Buddy") and print echo $dog->getName() . "\n".
Show example solution
Declare protected $name in Animal, Dog extends Animal, getName returns $this->name.
Example solution:
<?php
// Define Animal and Dog classes
class Animal {
protected string $name;
public function __construct(string $name) {
$this->name = $name;
}
}
class Dog extends Animal {
public function getName(): string {
return $this->name;
}
}
$dog = new Dog("Buddy");
echo $dog->getName() . "\n";
Test yourself
-
From where can a protected property be accessed?
- From inside the declaring class and its subclasses
- Only from inside the declaring class
- From anywhere outside the class
- Only at file level, from outside the class
Show answer
From inside the declaring class and its subclasses — Correct. protected members are reachable from the class and its subclasses.
-
Declare a protected property
class Animal {
____
}
Show answer
class Animal {
protected $name;
}
-
Match the protected expressions
- protected property
- Class and subclasses
- Outside access
- Triggers fatal error
- Inheritance with extends
- Grants protected access
- Parent $this->name
- In-class access
Next lesson: private access
