asked on

C# SOLID and best practices

Hello!
I need advice for SOLID principles and programming best practices.

I have two classes inherited from one main class. Objects of this classes are in List. I need beautifull solution to print information about this classes

Class Entity

class Entity
{
       
}

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Class Person

sealed class Person : Entity
{
       internal FirstName {get; set;}
       internal LastName {get; set;}

       public override string ToString()
        {
            return $"FirstName ={FirstName } LastName  = {LastName } ";
        }
 }

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Class Car

sealed class Car: Entity
{
       internal Name {get; set;}
       internal MaxSpeed {get; set;}

       public override string ToString()
        {
            return $"Name ={Name } MaxSpeed = {MaxSpeed } ";
        }
}

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Class Writer

sealed class Writer
{
    internal void Write()
    {
        List<Entity> entities= new List<Entity>();
       // add some persons..
      // add some cars...
       StreamWriter writer = new StreamWriter("qwe.txt");
       foreach (Entity e in entities)
       {
            writer.WriteLine(e.ToString());
       }
    }
}

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In real case there is complex logic in method ToString. And some other objects are using in method ToString()

it_saige

You can have your base class override ToString() and then call a simple extension method to return the properties formatted however you want; e.g. -

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

namespace EE_Q29180515
{
    class Program
    {
        static void Main(string[] args)
        {
            var person = new Person { FirstName = "Bob", LastName = "Ross" };
            var car = new Car { Name = "FastCar", MaxSpeed = 220 };

            Console.WriteLine(person);
            Console.WriteLine(car);

            Console.ReadLine();
        }
    }

    class Entity
    {
        public override string ToString()
        {
            return $"{{ {this.GetPropertiesString()} }}";
        }
    }

    sealed class Person : Entity
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }
    }

    sealed class Car : Entity
    {
        public string Name { get; set; }
        public int MaxSpeed { get; set; }
    }

    static class Extensions
    {
        public static string GetPropertiesString<T>(this T source)
        {
            return string.Join(", ", from property in source.GetType().GetProperties() select $"{property.Name}: {property.GetValueOrValues(source)}");
        }

        static string GetValueOrValues(this PropertyInfo property, object source)
        {
            var value = property.GetValue(source);
            if (ReferenceEquals(value, null))
            {
                return string.Empty;
            }
            else if (Equals(property.PropertyType, typeof(string)) && typeof(IEnumerable<>).IsAssignableFrom(property.PropertyType))
            {
                return $"{{ {string.Join(", ", from item in value as IEnumerable<object> select item)} }}";
            }
            else
            {
                return value.ToString();
            }
        }
    }
}

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Produces the following output -

-saige-

Chris Stanyon

What problem are you trying to solve here. The code you already have will work. It will call ToString() on each of your derived classes, and output the correct info.

Misha

ASKER

Thank you for response!

@it_saige
There is complex logic in each overriding method ToString(). There is no identical to all classes method to print each property.
If I use your solutin I should write something like this:

 public static string GetPropertiesString<T>(this T source)
        {
         if (source is Peson)
          {
            // print special logic for Peson
          }

         if (source is Car)
         {
            // print special logic for Car

          }
/// a lot of other classes
        }

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I think it is not the best practices..

@Chris Stanyon
I want to find the best solution. My overriding method ToString() have a complex logic. I think, it is not good to stay this method in classes, which are only intended for storage data.

@All
I think there should be other classes for print Person , Car and other objects.... May be..
And each implements interface for printing special object .... May be...

SOLUTION

it_saige

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ASKER CERTIFIED SOLUTION

Chris Stanyon

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Misha

ASKER

Thank you very mach!