Exposing an Immutable and Mutable Record Class C#

Question

I would like to write a set of c# record classes that offer both a Immutable and Mutable version of themselves.
This is similar to how there is a List and ReadOnlyList offered in c# (yes, arguably not quite as safe as the caller can still cast to the mutable version, but I am okay with that and that is not the heart of my question)

There are a few issues that I am running into in my implementations that I've tried so far:
Implement with Interfaces

    public record class MutableRecord : IReadOnlyRecord
    {
        public int ValueTypeProperty { get; set; }

        // This is is one problem. In the Mutable Record I would like to expose the Mutable 
        // version of the other record type. As opposed to the readonly interface.

        // public OtherMutableRecord RefernceTypeProperty { get; set; }
        public IReadOnlyRecord RefernceTypeProperty { get; set; }
    }

    public interface IReadOnlyOtherRecord
    {
        int SomeData { get; }
    }

    public record class OtherMutableRecord : IReadOnlyOtherRecord
    {
        public int SomeData { get; set; }
    }

Implementation with Base Classes
I tried swapping out the above interfaces with base classes and then using the new keyword to achieve implementation hiding. But c# doesn't allow for multiple inheritance. In many cases I have classes which need to derive from the ReadOnlyBase class and the other base class (used for other operations in the code, such as storing common objects in a List). So ideally the interface implementation would be best, but I can't get around the interface requiring a specific type.

This article should help you clarify the "record" concept: daveabrock.com/2020/11/02/csharp-9-records-immutable-default — D A
– D A, Commented Feb 12, 2024 at 15:34

JonasH · Accepted Answer · 2024-02-12 15:36:00Z

0

you can use explicit interface implementation to use expose different properties or levels of access based on the reference type:

public record class MutableRecord : IReadOnlyRecord
{
    public int ValueTypeProperty { get; set; }

    IReadOnlyOtherRecord IReadOnlyRecord.RefernceTypeProperty => ReferenceTypeProperty;
    public OtherMutableRecord ReferenceTypeProperty { get;  set;}
}

Note that "immutable" and "readonly" means slightly different things. The former implies that the object never changes, while the later that you cannot change it.

answered Feb 12, 2024 at 15:36

JonasH

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2 Comments

sdub0800 Over a year ago

Thank you for the reply. I think this works for my application! Thank you!!!

sdub0800 Over a year ago

Also thank you for the comment about immutability and readonly. I completely agree with the slight difference you point out and it is an important one. I will likley update my class names or something to make the intent more clear to the other developers on my team

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