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textYash

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•Created by textYash on 7/27/2024 in #help

Enum based Singleton

This is the description for my job training task:

Implement the Singleton class using the Enum approach to create a thread-safe Singleton instance without the need for lazy initialization or explicit locking.

Write a program to demonstrate that the Singleton instance is created only once and accessed safely by multiple threads using the Enum approach.

Implement the Singleton class using the Enum approach to create a thread-safe Singleton instance without the need for lazy initialization or explicit locking.

Write a program to demonstrate that the Singleton instance is created only once and accessed safely by multiple threads using the Enum approach.

I don't understand how to implement this. I find myself coding the same old implementation with a static backing field. Not here to get my homework done. I'm genuinely trying to learn

15 replies

CC#

•Created by textYash on 7/26/2024 in #help

Purpose of Dependency Injection

In this example what's the benefit of DI here. I can just create instances of EmailService and MessagingService class and call the SendMessage method on them without having to create an extra instance of the NotificationService class.

namespace basic_programs{
    interface IMessagingService {
        string SendMessage(string message);
    }
    class EmailService : IMessagingService {
        public string SendMessage(string message) {
            return $"Email sent: {message}";
        }
    }
    class SMSService : IMessagingService {
        public string SendMessage(string message) {
            return $"SMS sent: {message}";
        }
    }
    class NotificationService(IMessagingService messaging_service)
    {
        private readonly IMessagingService _messagingService = messaging_service;

        public string SendNotification(string message) {
            return _messagingService.SendMessage(message);
        }
    }
    class Lab23 {
        public static void NotificationDemo() {
            NotificationService email_service = new(new EmailService());
            NotificationService sms_service = new(new SMSService());
            System.Console.WriteLine(email_service.SendNotification("Hello"));
            System.Console.WriteLine(sms_service.SendNotification("Hello"));
        }
    }
}

namespace basic_programs{
    interface IMessagingService {
        string SendMessage(string message);
    }
    class EmailService : IMessagingService {
        public string SendMessage(string message) {
            return $"Email sent: {message}";
        }
    }
    class SMSService : IMessagingService {
        public string SendMessage(string message) {
            return $"SMS sent: {message}";
        }
    }
    class NotificationService(IMessagingService messaging_service)
    {
        private readonly IMessagingService _messagingService = messaging_service;

        public string SendNotification(string message) {
            return _messagingService.SendMessage(message);
        }
    }
    class Lab23 {
        public static void NotificationDemo() {
            NotificationService email_service = new(new EmailService());
            NotificationService sms_service = new(new SMSService());
            System.Console.WriteLine(email_service.SendNotification("Hello"));
            System.Console.WriteLine(sms_service.SendNotification("Hello"));
        }
    }
}

I asked AI then it just mentioned: 1. some theoretical information about how DI has loose coupling and all but couldn't prove any benefit in the code. 2. how I can independently test the NotificationService but I can just independently test MessagingService & EmailService. 3. how adding features to the MessagingService & EmailService can cause problems but couldn't show me how it can cause problems in the code.

24 replies

CC#

•Created by textYash on 5/23/2024 in #help

Unable to add a new Controller in Visual Studio

26 replies

DTDrizzle Team

•Created by textYash on 4/11/2024 in #help

How to call a method based on a condition?

I am running two almost similar queries based on a condition. In one of the condition I'm calling the where method and in the other one I'm not. How can I reduce duplicacy by having just one query that works for both conditions? Basically calling the where method only if a condition holds.

if (id === -1)
    chunk = await db
        .select({
            id: posts.id,
            content: posts.content,
        })
        .from(posts)
        .orderBy(desc(posts.id))
        .limit(6);
else
    chunk = await db
        .select({
            id: posts.id,
            content: posts.content,
        })
        .from(posts)
        .where(lt(posts.id, id) && eq(posts.hidden, hidden))
        .orderBy(desc(posts.id))
        .limit(6);

if (id === -1)
    chunk = await db
        .select({
            id: posts.id,
            content: posts.content,
        })
        .from(posts)
        .orderBy(desc(posts.id))
        .limit(6);
else
    chunk = await db
        .select({
            id: posts.id,
            content: posts.content,
        })
        .from(posts)
        .where(lt(posts.id, id) && eq(posts.hidden, hidden))
        .orderBy(desc(posts.id))
        .limit(6);

4 replies

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