Simplify Overriding Equals(), GetHashCode() in C# for Better Maintainability

Question

I find my self overriding Equals() and GetHashCode() frequently to implement the semantic that business objects with identical property values are

Answer 1

MSDN actually doesn't say "don't overload Equals et al for mutable types". It used to say that, but now it says:

When you define a class or struct, you decide whether it makes sense to create a custom definition of value equality (or equivalence) for the type. Typically, you implement value equality when objects of the type are expected to be added to a collection of some sort, or when their primary purpose is to store a set of fields or properties.

http://msdn.microsoft.com/en-us/library/dd183755.aspx

Still, there are complexities surrounding stability of the hash code while an object participates in a hashed collection (Dictionary<T,U>, HashSet<T>, etc.).

I decided to opt for the best of both worlds, as outlined here:

https://stackoverflow.com/a/9752155/141172

Answer 2

I find my self overriding Equals() and GetHashCode() frequently

• MSDN says : don't overload Equals et al for mutable types

Is ^ adequate given that the contributing component values are well-distributed?

• Yes, but hey are not always well distributed. Consider int properties. Shifting with some (small) prime numbers is advised.

Answer 3

Perhaps I'm confused here, but shouldn't the on null check return a 1 instead of a 0 in the GetHashCode override?

So

MyStringProp == null ? 0 : MyStringProp.GetHashValue()

should be

MyStringProp == null ? 1 : MyStringProp.GetHashValue()