Question

I need to perform this operation many times on my data:

public void AddBehavior(BehaviorTypes type)
{
    if (Enum.IsDefined(typeof(BehaviorTypes), type))
    {
    switch (type)
    {
        case BehaviorTypes.render:
            return new renderable();
        break;   
    }
}

That is two explicit function calls and an object boxing/unboxing operation! This operation is too expensive just to bounds check an enum. Does anyone know a cheaper alternative?

Answer 1

A pretty standard trick is to add members to the enum declaration that specify the first and last value:

enum BehaviorTypes {
    First = One,    
    One = 1,
    Two,
    Three,
    Last = Three
}

Now it is a superfast test, takes about a nanosecond:

public void AddBehavior(BehaviorTypes type)
{
    if (type >= BehaviorTypes.First && type <= BehaviorTypes.Last) {
       // etc..
    }
}

Do note that your switch statement already eliminates the need for this check.