CODEWITHSUNDEEP
c#nhibernate
weston
weston

Reputation: 54791

Implementing ICompositeUserType for immutable type

I have an immutable Money type (ammount and currency) and I'm copying an example I saw here.

They implement the deep copy like so:

public object DeepCopy(object value)
{
    return new Money(((Money) value).Amount, ((Money) value).Currency);
}

Which is pointless and inefficient for immutables. But as I don't know the NHibernate libs inside out, I want to know if it is nessasary, and if it's safe to do this:

public object DeepCopy(object value)
{
    return value;
}

The only difference I can foresee is if somewhere in NHibernate they are relying on object's != operator returning true. But that would be nasty, so I doubt that's going on, but I'd like confirmation.

Also, please note my money is a class, not a struct.

Upvotes: 0

Views: 108

Answers (1)

Firo
Firo

Reputation: 30813

DeepCopy is there to have a copy for change tracking which is pointless for immutable types so your implementation is typical for all immutable types

public bool IsMutable
{
    get { return false; }
}

public object DeepCopy(object value)
{
    return value;
}

Upvotes: 1

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