Compare two System.Enum of type T

Question

I am pretty close to understand Generics now (I think).
However, just figured that System.Enum is not easy to implement as a generic type. I have this class:

<         


        

Answer 1

You are trying to perform a reference comparison on a value type (struct), use Equals for equality instead:

public Button<TEnum> GetButton(TEnum Identifier) {
    var button = _buttons
        .Where(b => EqualityComparer<TEnum>.Default.Equals(b.Identifier, Identifier))
        .FirstOrDefault();

    if (button == null)
        Debug.Log("'" + GetType().Name + "' cannot return an <b>unregistered</b> '" + typeof(Button<TEnum>).Name + "' that listens to '" + typeof(TEnum).Name + "." + Identifier.ToString() + "'.");
    return button;
}

The button.Identifier == Identifier statement cannot be performed, because the == operator does not exist for structs. On a class it would have performed a reference comparison.

And as @JeppeStigNielsen noted in his answer, to prevent a boxing equality comparison, it is better to use the EqualityComparer<TEnum>.Default.Equals method.

Answer 2

Instead of the impossible

button.Identifier == Identifier

you should use

EqualityComparer<TEnum>.Default.Equals(button.Identifier, Identifier)

This avoids boxing the value into an object box (or IComparable box).