1.3 Zoo Instruction

Task 1 — Give each zoo guest a wallet

Step 1 — Add Wallet

Add Wallet.cs to the existing Business Classes folder. Keep the current project namespace, XML documentation style, and StyleCop suppression pattern.

public decimal MoneyBalance;

1. Add Wallet.cs to the Business Classes folder.
2. Add the documented MoneyBalance : decimal field.
3. Do not add properties or constructors.

Step 2 — Add Guest

public double PortionSize;
public int Age;
public string Name;
public Wallet Wallet;

public void Eat()
{
    // No state change is needed for this example.
}

1. Add Guest.cs to the Business Classes folder.
2. Add PortionSize, Age, Name, and the Wallet reference.
3. Add the current parameterless Eat() method.

Step 3 — Connect the visitor to Zoo

public Guest Visitor;

1. Add the documented Visitor : Guest relationship to Zoo.

Step 4 — Create the current visitors and wallets

1. Create Darla and her Wallet in the Como Zoo setup flow.
2. Create Dave and his Wallet in the San Diego Zoo setup flow.

Check Your Work

• Build.
• Confirm ComoZoo.Visitor.Name = "Darla" and ComoZoo.Visitor.Wallet.MoneyBalance = 5.25m.
• Confirm SanDiegoZoo.Visitor.Name = "Dave" and SanDiegoZoo.Visitor.Wallet.MoneyBalance = 3.75m.
• Confirm the two guests reference separate Wallet objects.

Task 2 — Pay for one feeding transaction

Step 1 — Add RemoveMoney()

public void RemoveMoney()
{
    this.MoneyBalance -= 2.0m;
}

The m suffix makes 2.0m a decimal. If the balance starts at 5.25m, one call produces 3.25m.

1. Add the documented parameterless void RemoveMoney() method to Wallet.
2. Keep the fixed 2.0m subtraction inside Wallet.

Check Your Work

• Build.
• Confirm RemoveMoney() belongs to Wallet.
• Confirm it subtracts exactly 2.0m and does not return a value.

Task 3 — Record money received by the vending machine

Step 1 — Add AddMoney()

public void AddMoney()
{
    this.MoneyBalance += 2.0m;
}

1. Add AddMoney() to VendingMachine.
2. Keep the fixed 2.0m addition inside the vending machine.

Check Your Work

• Build.
• Confirm the method changes the current vending machine's MoneyBalance.
• Confirm it has no custom parameters and returns void.

Task 4 — Sell one pound of animal food

Step 1 — Add SellFood()

public void SellFood()
{
    this.AddMoney();
    this.FoodStock -= 1.0;
}

this.AddMoney() calls another method on the same VendingMachine object. When that call returns, execution continues with the FoodStock subtraction.

1. Add SellFood() to VendingMachine.
2. Call AddMoney() before reducing FoodStock.
3. Subtract exactly 1.0 from the current food stock.

Check Your Work

• Build.
• Confirm SellFood() calls AddMoney().
• Confirm one sale adds 2.0m to money and removes 1.0 pound of food.

Task 5 — Let the featured animal eat

Step 1 — Add the current weight-gain percentage

public double EatWeightGainPercentage = 0.8;

Step 2 — Add Eat()

public void Eat()
{
    this.Weight = this.Weight + (this.Weight * this.EatWeightGainPercentage);
}

For Dolly: 35.3 + (35.3 × 0.8) = 63.54.

For Patti: 3.27 + (3.27 × 0.8) = 5.886.

1. Add or confirm EatWeightGainPercentage = 0.8 in Animal.
2. Add the parameterless void Eat() method.
3. Keep the weight calculation inside Animal.

Check Your Work

• Build.
• Confirm Dolly changes from 35.3 to 63.54 after one call.
• Confirm Patti changes from 3.27 to 5.886 after one call.

Task 6 — Connect the Como Zoo feeding action

Step 1 — Confirm the button

<Button x:Name="darlaFeedDingoButton" Content="Darla, feed dingo" Click="darlaFeedDingoButton_Click"/>

Step 2 — Complete the event handler

public void darlaFeedDingoButton_Click(object sender, RoutedEventArgs e)
{
    this.ComoZoo.Visitor.Wallet.RemoveMoney();
    this.ComoZoo.AnimalSnackMachine.SellFood();
    this.ComoZoo.FeaturedAnimal.Eat();
}

1. Call RemoveMoney() on Darla's wallet.
2. Call SellFood() on the Como vending machine.
3. Call Eat() on Dolly.
4. Keep the calls in that order.

Check Your Work

• From a fresh Como Zoo without refilling, confirm Darla changes 5.25 → 3.25.
• Confirm vending money changes 0 → 2.00.
• Confirm food stock changes 0 → -1.0.
• Confirm Dolly changes 35.3 → 63.54.

Task 7 — Connect the San Diego Zoo feeding action

Step 1 — Confirm the button

<Button x:Name="daveFeedPlatypusButton" Content="Dave, feed platypus" Click="daveFeedPlatypusButton_Click"/>

Step 2 — Complete the event handler

public void daveFeedPlatypusButton_Click(object sender, RoutedEventArgs e)
{
    this.SanDiegoZoo.Visitor.Wallet.RemoveMoney();
    this.SanDiegoZoo.AnimalSnackMachine.SellFood();
    this.SanDiegoZoo.FeaturedAnimal.Eat();
}

1. Call the three existing methods through the San Diego object graph.
2. Keep the transaction order the same as Como Zoo.

Check Your Work

• From a fresh San Diego Zoo without refilling, confirm Dave changes 3.75 → 1.75.
• Confirm vending money changes 0 → 2.00.
• Confirm food stock changes 0 → -1.0.
• Confirm Patti changes 3.27 → 5.886.

Task 8 — Trace the feeding transaction

Step 1 — Trace the wallet call

Set a breakpoint on:

this.ComoZoo.Visitor.Wallet.RemoveMoney();

1. Run the application and create a fresh Como Zoo.
2. Click Darla, feed dingo and stop at the breakpoint.
3. Step Into Wallet.RemoveMoney().
4. Inspect MoneyBalance before and after the subtraction.
5. Step Out to return to the event handler.

Step 2 — Trace the nested vending-machine call

1. Step Into VendingMachine.SellFood().
2. Step Into this.AddMoney() from inside SellFood().
3. Open the Call Stack while paused in AddMoney().

VendingMachine.AddMoney()
VendingMachine.SellFood()
MainWindow.darlaFeedDingoButton_Click(...)

1. Step through the money addition.
2. Step Out to SellFood() and execute the food-stock subtraction.

Step 3 — Trace the animal call

1. Return to the event handler and Step Into Animal.Eat().
2. Inspect Dolly's Weight and EatWeightGainPercentage before the calculation.
3. Execute the calculation and confirm Weight = 63.54.
4. Press F5 (Continue) when the trace is complete.

Check Your Work

• You can explain how the event handler calls three different object behaviors.
• You can identify the nested SellFood() → AddMoney() path in the Call Stack.
• You can use Step Out to return to a caller.

Task 1 — Add a food bag to a vending machine

Step 1 — Add AddFoodBag()

public void AddFoodBag()
{
    this.FoodStock += this.BagSize;
}

1. Add AddFoodBag() to VendingMachine.
2. Use the current machine's BagSize; do not duplicate the value inside the UI handler.

Check Your Work

• Build.
• With BagSize = 65 and FoodStock = 0, one call produces 65.
• A second call produces 130.

Task 2 — Refill the Como Zoo vending machine

Step 1 — Confirm the button and handler

<Button x:Name="floraFillVendingMachineButton" Content="Flora, fill vending machine" Click="floraFillVendingMachineButton_Click"/>

public void floraFillVendingMachineButton_Click(object sender, RoutedEventArgs e)
{
    this.ComoZoo.AnimalSnackMachine.AddFoodBag();
}

1. Call AddFoodBag() on ComoZoo.AnimalSnackMachine.

Check Your Work

• Create a fresh Como Zoo.
• Confirm FoodStock = 0, click the refill button once, and confirm FoodStock = 65.

Task 3 — Refill the San Diego Zoo vending machine

Step 1 — Confirm the button and handler

<Button x:Name="bettyFillVendingMachineButton" Content="Betty, fill vending machine" Click="bettyFillVendingMachineButton_Click"/>

public void bettyFillVendingMachineButton_Click(object sender, RoutedEventArgs e)
{
    this.SanDiegoZoo.AnimalSnackMachine.AddFoodBag();
}

1. Call AddFoodBag() on SanDiegoZoo.AnimalSnackMachine.

Check Your Work

• Create a fresh San Diego Zoo.
• Confirm FoodStock = 0, click the refill button once, and confirm FoodStock = 65.

Task 4 — Verify repeated refills

Step 1 — Refill more than once

1. Create a fresh Como Zoo and confirm FoodStock = 0.
2. Refill once and confirm FoodStock = 65.
3. Refill again and confirm FoodStock = 130.

Step 2 — Combine refill and feed

1. Create a fresh Como Zoo.
2. Refill once.
3. Feed Dolly once.

Check Your Work

• Darla wallet = 3.25.
• Como vending MoneyBalance = 2.00.
• Como vending FoodStock = 64.0.
• Dolly Weight = 63.54.

Task 1 — Change pregnancy state through behavior

Step 1 — Add MakePregnant()

public void MakePregnant()
{
    this.IsPregnant = true;
}

1. Add the documented parameterless void MakePregnant() method to Animal.

Check Your Work

• Build.
• Confirm the method changes the current animal's IsPregnant field to true.

Task 2 — Represent animal movement as behavior

Step 1 — Add Move()

public void Move()
{
}

1. Add Move() to Animal.
2. Leave the body empty for Zoo 1.3.

Check Your Work

• Build.
• Confirm the method is parameterless and returns void.

Task 3 — Use MakePregnant() when creating the featured animals

Step 1 — Call the behavior for Dolly

this.ComoZoo.FeaturedAnimal.MakePregnant();

Step 2 — Call the behavior for Patti

this.SanDiegoZoo.FeaturedAnimal.MakePregnant();

1. Call MakePregnant() after Dolly is initialized.
2. Call MakePregnant() after Patti is initialized.
3. Do not directly assign IsPregnant = true from MainWindow for these actions.

Check Your Work

• Create each zoo.
• Confirm both featured animals have IsPregnant = true.

Task 1 — Create the Como Zoo through a focused method

Step 1 — Add the creation method

public void CreateComoZoo()

Move the existing Como creation statements into this method. Do not rewrite the entire object graph from memory; preserve the current working relationships and values.

1. Create CreateComoZoo() in MainWindow.
2. Move the existing Como object-creation statements into the method.
3. Preserve the current relationships and values shown above.
4. Call MakePregnant() after Dolly is initialized.

Check Your Work

• Build.
• Confirm Como InitialTemperature = 77.0.
• Confirm vending FoodStock and MoneyBalance begin at their default numeric value 0.
• Confirm Dolly is pregnant through MakePregnant().

Task 2 — Connect the New Como Zoo control

Step 1 — Simplify the event handler

public void newComoZooButton_Click(object sender, RoutedEventArgs e)
{
    this.CreateComoZoo();
}

1. Replace the detailed Como setup inside the event handler with the call to CreateComoZoo().

Check Your Work

• Build and run.
• Click New Como Zoo and confirm the complete zoo is still created.

Task 3 — Create the San Diego Zoo through a focused method

Step 1 — Add the creation method

public void CreateSanDiegoZoo()

1. Create CreateSanDiegoZoo() in MainWindow.
2. Move the existing San Diego object-creation statements into the method.
3. Preserve the current relationships and values shown above.
4. Call MakePregnant() after Patti is initialized.

Check Your Work

• Build.
• Confirm San Diego InitialTemperature = 77.0.
• Confirm Patti is pregnant through MakePregnant().

Task 4 — Connect the New San Diego Zoo control

Step 1 — Simplify the event handler

public void newSanDiegoZooButton_Click(object sender, RoutedEventArgs e)
{
    this.CreateSanDiegoZoo();
}

1. Replace the detailed San Diego setup inside the event handler with the call to CreateSanDiegoZoo().

Check Your Work

• Build and run.
• Click New San Diego Zoo and confirm the complete zoo is still created.

Task 5 — Trace a method called from another method

Step 1 — Enter the creation method

Set a breakpoint on:

this.CreateComoZoo();

1. Run the application and click New Como Zoo.
2. Step Into CreateComoZoo().
3. Continue until execution reaches this.ComoZoo.FeaturedAnimal.MakePregnant();.

Step 2 — Enter the animal method

1. Step Into Animal.MakePregnant().
2. Inspect IsPregnant before and after the assignment.
3. Open the Call Stack.

Animal.MakePregnant()
MainWindow.CreateComoZoo()
MainWindow.newComoZooButton_Click(...)

1. Step Out to return to CreateComoZoo().
2. Step Out again to return to the event handler.

Check Your Work

• You can explain the three-level call path from the UI event to the animal method.
• You can identify the current method and its callers in the Call Stack.

Finish and Submit

Final Como transaction check

1. Create a fresh Como Zoo.
2. Refill the vending machine once.
3. Feed Dolly once.
4. Confirm Darla wallet = 3.25.
5. Confirm vending MoneyBalance = 2.00 and FoodStock = 64.0.
6. Confirm Dolly Weight = 63.54 and IsPregnant = true.

Final San Diego transaction check

1. Create a fresh San Diego Zoo.
2. Refill the vending machine once.
3. Feed Patti once.
4. Confirm Dave wallet = 1.75.
5. Confirm vending MoneyBalance = 2.00 and FoodStock = 64.0.
6. Confirm Patti Weight = 5.886 and IsPregnant = true.

Debugger check

1. Confirm you can set a breakpoint.
2. Confirm you can Step Over, Step Into, and Step Out.
3. Confirm you can Continue with F5.
4. Confirm you can inspect state before and after a method.
5. Confirm you can use the Call Stack to identify nested calls.
6. Build the solution and resolve compilation errors and project-style warnings introduced by your work.
7. Stop debugging and save all files.