Publisher-subscriber execution model in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a delegate named Notify.

C Sharp (C#)

public delegate void [1]();

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ANotify

BEventHandler

CSubscriber

DPublisher

Attempts:

3 left

💡 Hint

Common Mistakes

Using a class name instead of a delegate name.

Using a built-in delegate name incorrectly.

The delegate named Notify is declared to define the signature for event handlers.

2fill in blank

medium

Complete the code to declare an event named OnNotify using the Notify delegate.

C Sharp (C#)

public event [1] OnNotify;

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ANotify

BEventHandler

CAction

DEventArgs

Attempts:

3 left

💡 Hint

Common Mistakes

Using a delegate type that does not match the event signature.

Using a built-in delegate instead of the custom one.

The event OnNotify is declared using the Notify delegate type.

3fill in blank

hard

Fix the error in the code to correctly subscribe a method named HandleNotification to the OnNotify event.

C Sharp (C#)

publisher.OnNotify [1]= HandleNotification;

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A-

B+=

C==

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' instead of '+='.

Using '-' or '==' operators incorrectly.

The correct operator to subscribe a method to an event is +=.

4fill in blank

hard

Fill both blanks to raise the OnNotify event safely.

C Sharp (C#)

if (OnNotify [1] null)
{
    OnNotify[2]();
}

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A!=

B==

C()

D?.Invoke

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' instead of '!=' in the condition.

Calling the event directly without null check.

Check if the event is not null using != and invoke it safely using ?.Invoke().

5fill in blank

hard

Fill all three blanks to create a dictionary of subscribers with their names and subscribe them to the event.

C Sharp (C#)

var subscribers = new Dictionary<string, Notify>()
{
    {"Alice", [1],
    {"Bob", [2]
};

foreach (var subscriber in subscribers)
{
    publisher.OnNotify [3]= subscriber.Value;
}

Drag options to blanks, or click blank then click option'

AAliceHandler

BBobHandler

C+=

D-=

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong operator to subscribe or unsubscribe.

Using incorrect method names for subscribers.

Subscribers are methods named AliceHandler and BobHandler. They are subscribed to the event using +=.