Magic Constants

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 display recipe. 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 two string 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