Wrapping Up

How did you do? 0:00 Let's take a look at my solution. 0:01 In each media type subclass, 0:03 I replaced the GetDisplayText method with a DisplayText computed property. 0:05 First, the Album class. 0:10 Like I did in the walk through of my solution for the first challenge, 0:15 I'll show an example of both the regular and expression body property syntax. 0:19 I started with defining the computed property using regular property syntax. 0:24 First, I stubbed out the property and its getter. 0:33 Remember, we're creating a read-only property whose value is computed using 0:50 other properties. 0:54 So we only need to define a getter. 0:56 For the properties getter implementation, I cut and 0:59 pasted the GetDisplayText method body into the body of the getter. 1:02 I'll select that code and press Tab to fix the indentation. 1:15 And let's go ahead and remove what's left of the GetDisplayText method, 1:19 as it's no longer needed. 1:23 And that completed my DisplayText computed property. 1:30 To convert this property to an expression body property, we need to rewrite 1:35 the code and the getter as a single expression or a single line of code. 1:39 While it's possible to do, the resulting code would not be very readable, so 1:44 I'll hold off on showing that example. 1:48 If you want to see what it'd look like, see the teacher's notes. 1:50 But while I was working on converting the GetDisplayText method to a computed 1:55 property, I noticed an opportunity to improve its implementation. 1:59 This code here related to loading media library items is repeated in both 2:09 the Book and Movie classes. 2:14 So I move this code into the MediaType base class. 2:17 To start, I added 2:23 an OnLoanDisplayText 2:27 computed property. 2:32 Then I copied and pasted the repeated code into the getter. 2:48 At this point, I had a little bit of clean up to do on this code. 3:01 Instead of impending onto the text variable, which is no longer defined 3:10 in this code block, I just returned these string literals. 3:14 And I added an else statement and returned an empty string if the item isn't online. 3:24 Then I switch back to the Album class and updated the DisplayText Computed property. 3:41 We can now remove all of this code. 3:56 And we can replace our text variable with the return keyword. 4:05 And at the end of this line, we can append the OnLoanDisplayText property. 4:12 Isn't that code easier to read and understand? 4:22 After that change, 4:26 it was easy to update the property to an expression body property. 4:27 After the DisplayText property name I added =>, 4:32 which is known as a fat arrow, and 4:37 then removed everything up to the Album string literal. 4:40 And after the OnLoanDisplayText property and the semicolon, 4:52 I removed the last two closing curly braces. 4:56 The line of code is a little bit long, so I'm gonna put my 4:58 right before the album string literal and start a new line. 5:03 And there, that's our completed expression body property. 5:09 To update the other MediaType subclasses, 5:14 I copied and pasted the expression body property to the Book and Movie classes. 5:17 We need to change Album, here, to Book, and 5:29 this Artist property to Author. 5:33 Then we can remove the GetDisplayText method. 5:37 Then the Movie class, 5:45 Paste from the clipboard, Change this Album string to Movie. 5:51 And replace the Artist property, here, with Director, and 5:59 remove the GetDisplayText method. 6:03 For the bonus challenge, I opened the MediaLibrary class file, 6:12 And I stubbed out a number of items expression body computed property. 6:18 Public, so it's accessible from outside of the class. 6:26 Int for its data type. 6:31 Then the name of the property, NumberOfItems. 6:33 Then an = and a >, otherwise know as a fat error, 6:39 then I return the length of the items array. 6:44 So _items.link. 6:48 Moving on to the Program.cs file. 6:54 Scrolling down to the Display method, I replaced all the calls to 6:59 the GetDisplayText method with the DisplayText property. 7:03 And I added a call to the Console.WriteLine 7:20 method in order to test the MediaLibrary NumberOfItems property. 7:26 And lastly, I compiled and ran my program in order to test my changes 7:49 Let's make one small change to make this output a little bit more readable. 8:12 So Console.WriteLine, and then let's add a string literal here, 8:19 # of items, followed by a colon and a space. 8:25 I'll save the file, 8:29 Compile and run my program again. 8:37 There, that makes it a little bit more readable. 8:42 So here's the number of items in our media library, and 8:44 then here is the rest of the expected output. 8:48 Congrats on completing this practice session. 8:52 Be sure to check out the next session in the series after you've completed 8:54 the six and final stage in the C# objects course. 8:59 Thanks for practicing with me and we'll see you next time. 9:02