CODEWITHSUNDEEP
c#pass-by-value
ViV
ViV

Reputation: 2118

Pass by Value in C#

How can I pass an object of a "MyClass" (C#) by Parameter-by-Value to a method? example:

MyClass obj = new MyClass();
MyClass.DontModify(obj); //Only use it!
Console.Writeline(obj.SomeIntProperty);

...

public static void DontModify(MyClass a)
{
    a.SomeIntProperty+= 100;// Do something more meaningful here
    return;
}

Upvotes: 18

Views: 47630

Answers (6)

KushalSeth
KushalSeth

Reputation: 4639

Created a Extention method

using System.Text.Json;    

namespace Student.Utilities 
{
    public static class CloneExtension
    {
        public static T Clone<T>(this T cloneable) where T : new()
        {
            var toJson = JsonSerializer.Serialize(cloneable);
            return JsonSerializer.Deserialize<T>(toJson);
        }
    }
}

Now, while calling, call it like this to pass the clone to another method:

public void CreateStudent(Student student) 
{
      Student clonedStudent = student.Clone<Student>();
      _repository.CreateStudent(clonedStudent);
}

Upvotes: 0

alsafoo
alsafoo

Reputation: 788

class Program
{
    static void Main(string[] args)
    {
        Person p1 = new Person()
        {
            Name = "Alsafoo",
            Address = new Address()
            {
                City = "Chicago"
            }
        };

        Person p2 = new Person(p1.Address);
        p2 = p1.GetClone(CloningFlags.Shallow);
        p2.Name = "Ahmed";
        p2.Address = new Address(){City = "Las Vegas"};
        Console.WriteLine("p1 first name: {1} --- p1 city: {2} {0}p2 first name: {3} ---- p2 city: {4}", 
            Environment.NewLine, p1.Name, p1.Address.City, p2.Name, p2.Address.City);
        Console.ReadKey();
    }
}
public class Person
{
    public Person()
    {}
    public Person(Address a)
    {
        Address = a;
    }
    public string Name { get; set; }
    public Address Address { get; set; }        
}

public class Address
{
    public string City { get; set; }
}

Download this extension https://www.nuget.org/packages/CloneExtensions/1.2.0

Upvotes: 0

Daniel Pe&#241;alba
Daniel Pe&#241;alba

Reputation: 31847

By default object types are passed by value in C#. But when you pass a object reference to a method, modifications in the object are persisted. If you want your object to be inmutable, you need to clone it.

In oder to do it, implement the ICloneable interface in your class. Here is a mock example of how to use ICloneable:

public class MyClass : ICloneable
{
  private int myValue;

  public MyClass(int val)
  {
     myValue = val;
  }

  public void object Clone()
  {
     return new MyClass(myValue);
  }
}

Upvotes: 17

Dan Lister
Dan Lister

Reputation: 2583

You could create a Clone method on your object to pass the return value to your method. C# cannot pass reference types by value so this might be a good alternative.

public MyClass CreateClone()
{
    return new MyClass() { SomeIntProperty = this.SomeIntProperty };
}

Upvotes: 4

MusiGenesis
MusiGenesis

Reputation: 75296

public static void DontModify(MyClass a)
{
    MyClass clone = (MyClass)a.Clone();
    clone.SomeIntProperty+= 100;// Do something more meaningful here
    return;
}

Upvotes: 6

Reed Copsey
Reed Copsey

Reputation: 564393

By default, it is passed by value. However, you're passing the object reference by value, which means you can still edit values within the object.

In order to prevent the object from being able to change at all, you would need to actually clone the object prior to passing it into your method. This would require you to implement some method of creating a new instance that is a copy of your original object, and then passing in the copy.

Upvotes: 9

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