Acceptance criteria
- A temperature-change delegate notifies the console when the birthing room temperature changes.
Use delegates to update the birthing room temperature in console.
Acceptance Criteria
1.Use delegates to update the birthing room temperature in console.
Problem
Solution
A
Make changes to the BirthingRoom, Zoo, and ConsoleHelper classes as specified in the diagram below.
public Action<double, double> OnTemperatureChange { get; set; }
B
In the BirthingRoom's Temperature setter
1
Store the current temperature field value in a local variable named previousTemp before setting the field to the new value.
2
After setting the temperature, call the OnTemperatureChange delegate and pass in the previousTemp variable and temperature field.
3
Check if the delegate is not null before calling it.
C
Bubble the birthing room temperatures up through the zoo.
1
In the zoo's constructor, after instantiating b168, plug in the HandleBirthingRoomTemperatureChange method to b168's OnTemperatureChange delegate.
This attaches the method to the delegate so that whenever the delegate (property) is called, the method will run.
this.b168.OnTemperatureChange += this.HandleBirthingRoomTemperatureChange;2
In the HandleBirthingRoomTemperatureChange method, call the OnBirthingRoomTemperatureChange delegate.
Pass the previousTemp and currentTemp parameters through.
D
Update the console.
1
In the ConsoleHelper's HandleBirthingRoomTemperatureChange method, write out the previousTemp and currentTemp to the console.
Console.WriteLine($"Previous temperature: {previousTemp:0.0}.");
Console.WriteLine($"New temperature: {currentTemp:0.0}.");2
In the AttachDelegates method, plug in the HandleBirthingRoomTemperatureChange method to the zoo's OnBirthingRoomTemperatureChange delegate.
3
The SetTemperature method now only needs to set the birthing room temperature and catch any exceptions that might occur.
Remove any code that writes temperatures to the console. Replace the code in the try block with the code below.
zoo.BirthingRoomTemperature = double.Parse(temperature);E
In the Main method of Program.cs, call the AttachDelegates method after
1
Initially creating the zoo
2
Restarting the zoo
3
Loading a zoo
F
Check your work
1
Set a breakpoint on the call to AttachDelegates in the Program.cs.
2
Run the console application.
3
Press F11 to step into AttachDelegates.
4
Press F10 to step over the line of code that plugs the Handle method into the OnChange method.
The OnBirthingRoomTemperature change delegate (property) now is the HandleBirthingRoomTemperatureChange method in the ConsoleHelper class.
5
Set a breakpoint in the SetTemperature method in the ConsoleHelper class on the line that sets the BirthingRoomTemperature.
6
Click Continue and type in the command 'temp 60'
7
Press F11 until you get to the null check for the OnTemperatureChange delegate in the Temperature property.
Ensure that the OnTemperatureChange delegate has the method HandleBirthingRoomTemperatureChange plugged into it.
8
Press F11 to step through the OnTemperatureChange getter and then into the HandleBirthingRoomTemperatureChange method in the Zoo class.
Ensure the OnBirthingRoomTemperatureChange delegate has the
HandleBirthingRoomTemperatureChange method plugged into it.
9
Press F11 to step through the OnBirthingRoomTemperatureChange getter and then into the HandleBirthingRoomTemperatureChange method in the ConsoleHelper class.
10
Click Continue. Ensure that the console has written the previous temp of 77 and the new temp of 60.
