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Object-Oriented PHP Basics

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Magic Constants

6:14 with Alena Holligan

Along with "Magic Methods", PHP also provides a large number of predefined constants to give us... a little more magic. These "Magic Constants" can provide details about our script and our environment. We'll look at a few "Magic Constants" that help us understand our classes and objects.

Documentation

Magic Constants

Challenge

Add you own magic constants to the __toString method.

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    Magic methods can be a lot of fun, as well as extremely powerful. 0:00
    But PHP gives us even more magic in the form of magic constants. 0:05
    PHP provides a large number of predefined constants to give us a little more magic. 0:10
    These special constants both start and end with double underscores, and 0:16
    are not case sensitive. 0:20
    But, if we start changing the case all over the place, 0:22
    it makes things very difficult to read. 0:26
    You should write all constants in uppercase. 0:29
    Magic constants can provide a lot of information. 0:32
    Let's take a look at a few of the most useful in relation to objects. 0:36
    Let's modify the to string method. 0:41
    Instead of only displaying the recipe title, 0:43
    let's give it a bit more information about the object itself. 0:46
    The first magic constant we'll use is class. 0:50
    Written __CLASS__. 0:54
    This gives us the name of the class itself. 1:00
    Let's use this in a message. 1:02
    Let's also remove our call to the displayRecipe. 1:37
    Now let's run our script. 1:44
    Now we see that you are calling a recipe object with the title, My First Recipe. 1:47
    Looks good so far. 1:53
    Let's add a little more magic. 1:54
    There are two constants that reference the file where the class is stored. 2:00
    The first one is __FILE__. 2:04
    This gives us the full path with the file name. 2:08
    We can get just the file name by combining that with the function, basename. 2:11
    We could use the function dir name with file as well to pull 2:19
    only the directory path. 2:23
    But we have another constant that you'll often see the __DIR__ or 2:25
    directory constant. 2:29
    This constant gives us the full path to the file without the file name. 2:33
    I use __DIR__ often when I want to link to another file 2:37
    within the same directory as this file. 2:41
    It works even if this file is included in another file. 2:43
    Let's add both of these to our message as well. 2:47
    Next, let's show specific information about where in the class we are currently 3:09
    looking. 3:13
    __LINE__ will tell us the current line number in the file and 3:15
    the __METHOD__ will tell us the name of the method we are using. 3:19
    Let's add these as well. 3:26
    Finally, let's show a list of the methods in case the user is looking for something. 3:50
    This is another place where we use a function in combination with 3:56
    a magic constant. 3:59
    get_class_methods. 4:00
    We then pass it the __CLASS__. 4:04
    Now let's add this to our output. 4:08
    Let's use the implode. 4:31
    When we finish, we want to return the output. 4:41
    Now we're ready to run our script again. 4:45
    Wonderful, we have a lot of information about our object that we can use to update 4:54
    the call to our object. 4:59
    For example, I can look through the list of methods and 5:01
    see the exact name of my getters and setters. 5:04
    For security purposes, 5:08
    you should not display the full directory path on a production server. 5:09
    It can give hackers much more information than you want. 5:14
    Let's add this toString method to our render class as well. 5:17
    Then we'll be able to show the methods that are available. 5:21
    Let's copy this. 5:26
    And we'll go in to render. 5:28
    We only want to say what methods are available. 5:33
    But let's change this so it tells us which type of object we're using. 5:38
    Now let's go back to our cookbook. 5:53
    Since we don't have an object, we can just echo new Render. 5:57
    And now let's run our code. 6:05
    Great, we see the results of the render object as well. 6:10

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