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Extending Object-Oriented PHP

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Using Multiple Classes

3:13 with Alena Holligan

When using multiple classes, there are several functions in PHP that will allow us to learn about those classes.

Documentation

  • get_class() - Returns the name of the class of an object
  • is_a() - Checks if the object is of this class or has this class as one of its parents
  • get_object_vars() - Gets the properties of the given object

You could also try some additional class/object functions

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    In the last video, we saw that we could easily swap out our new child class, 0:00
    where we use the parent. 0:04
    Let's take a closer look at the result. 0:06
    Open index.php. We'll start by adding a var_dump of 0:08
    the listings within the foreach loop. 0:12
    Let's preview this in the browser. 0:20
    Lets view the page source, and increase the font size. 0:25
    This shows us that the object itself is a listing premium object, but 0:29
    its variables are taken from the listing basics class. 0:36
    Let's take a look at a couple more functions that will tell us about 0:45
    our class. 0:48
    Var_dump get_class, 0:53
    This will give us the name of the object's class. 1:03
    We can also check if this object is of a certain type. 1:06
    We'll do a var_dump is_a, pass the listing, 1:09
    And then the class we wish to compare, ListingBasic. 1:18
    Let's preview this again. 1:24
    Now we see that it tells us that our class is a listing premium, but 1:28
    our check with the is a function, returns true. 1:32
    That's because listing premium is a child, and therefore a type of 1:36
    ListingBasic, and can be used wherever ListingBasic is used. 1:41
    We could also see in the status of these listings, 1:46
    that some of them are premium, And some of them are basic. 1:48
    Let's go back to our collection class and use ListingBasic for 1:55
    our basic listings, and ListingPremium for our premium listings. 1:59
    In the addListing method, we need to check the status. 2:08
    If isset status, 2:16
    And that same status, 2:23
    Is equal to premium, then we're going to use ListingPremium. 2:31
    If not, else, we're going to use listingBasic. 2:38
    Let's check this out in the browser once more. 2:51
    Now the listings that have a status of basic, are of a ListingBasic class. 2:55
    And those that have a status of premium, are of a ListingPremium class. 3:03
    We're ready to actually extend our child class in more than just name 3:08

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