readonly parameter with container Class (C#)

Question

Ok so let's say that I have a data container class

public class DataContainer {
      public Person person;
}

and we already create an instance of this class

DataContainer dataContainer = new DataContainer();
dataContainer.Person = new Person("Smith");

and we try to pass it in a method that we want to be able to only read the container and not modified

public void ExampleMethod(in DataContainer dataContainer){
   dataConainer.Person.name = "blablabla" //we don't want to be able to do that
   dataContainer = new DataContainer(); // this is not possible because of in keyword
}

I tried the in keyword but it doesn't have any effect on prohibiting changes on container...

P.S. : convert the container into a struct is no solution because it will become immutable

Answer 1

If you don't want to be able to modify the Person.Name, then you could simply use encapsulation.

I would design the Person class in the following way:

class Person
{
    public Person(string name)
    {
        Name = name;
    }

    public string Name { get; }
}

If this doesn't help, then the only other approach I see is to pass a DTO to ExampleMethod (which can be easily created using Automapper).

var dto = _mapper.Map<DataContainerDto>(dataContainer);
ExampleMethod(dto);

...

public void ExampleMethod(DataContainerDto dataContainer)
{
    // Nobody cares if I modify it,
    // because the original dataContainer reamains intact
    dataConainer.Person.name = "blablabla";
}