How to create immutable objects in C#?

Question

In a question about Best practices for C# pattern validation, the highest voted answer says:

I tend to perform all of my validation in the constructor

Answer 1

Declaring all fields readonly is a good step towards creating an immutable object, but this alone is not sufficient. This is because a readonly field can still be a reference to a mutable object.

In C# immutability is not enforced by the compiler. You just have to be careful.

Answer 2

An immutable value object is a value object that cannot be changed. You cannot modify its state, you have to create new ones

Check out Eric Lippert's blog:

Kinds of Immutability https://docs.microsoft.com/en-us/archive/blogs/ericlippert/immutability-in-c-part-one-kinds-of-immutability

Have a look at

Immutable object pattern in C# - what do you think?