Section 6 - Accessing properties and methods_PHP Tutorial

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Section 6 - Accessing properties and methods

Properties of an object instance are variables, just like other variables in PHP. But you must use the -> operator to reference them. There is no need to use the dollar sign $ before the attribute. For example, the line in 6.1 that prints the name attribute of the User object.

can be used with ->, if the properties of an object contain an object, you can use two -> operators to get the properties of the inner object. You can even use double-referenced strings to place these expressions Formula. Looking at the example in 6.5, the attribute room in the object House contains a set of Room objects. The

access method is similar to accessing the attribute. The -> operator is used to point to the method of the instance. In Example 6.1 Just call getLastLogin. The method execution is almost the same as the function outside the class.

If a class inherits from another class, the properties and methods in the parent class will be valid in the subclass, even if There are no declarations in the subclass. As mentioned before, inheritance is very powerful. If you want to access an inherited property, you only need to reference it as you would access the base class's own property, using the :: operator.

Copy code The code is as follows:

class Room
{ public $name;

function __construct($name="unnamed")
{ >
class House
{
//array of rooms
public $room;
}

//create empty house
$home = new house;

//add some rooms
$home->room[] = new Room("bedroom");
$home->room[] = new Room("kitchen");
$home->room[] = new Room("bathroom");

//show the first room of the house
print($home->room[0]->name );
?>



PHP has two special namespaces: the parent namespace points to the parent class, and the self namespace points to the current class. Example 6.6 shows how Use the parent namespace to call the constructor in the parent class. Also use self to call another class method in the constructor.

Copy code

The code is as follows:

class Animal //Animal
{
public $blood; //Hot-blooded or cold-blooded attribute
public $name;
public function __construct($blood, $ name=NULL)                                                        ->name = $name;
}
}                                                                                                                        

function __construct($furColor, $legs, $name=NULL)
{ {
parent::__construct("warm", $name);
$this->legs = $legs;
} }
}

class Dog extends Mammal
{ function __construct($furColor, $name)
                                                > parent::__construct($furColor, 4, $name);

self::bark();
}

function bark() {
print ("$this->name says 'woof!'");                                             ?>



Chapter 4 introduces how to call functions. For members of the object, the call is like this: If you need to determine the name of the variable at runtime, you can use $ Expressions like this->$Property. If you want to call a method, you can use $obj->$method().

You can also use the -> operator to return the value of a function , which was not allowed in previous versions of PHP. For example, you could write an expression like this: $obj->getObject()->callMethod(). This avoids the use of an intermediate variable and also helps For implementing certain design patterns, such as Factory pattern.



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* +---------------------- -------------------------------------------------- -------+ |=This article is for Haohappy reading CorePHP Programming |=Notes from the ClassesandObjects chapter|=Translated mainly + personal...