C#•2y ago

Change function behavior depending on class' generic type.

Hello! I was wondering if there was a way to change the behavior of a function in a class with a generic type. I was originally looking into overloading but didn't have any luck. Is what I'm trying to do possible?

public class Lerpable<T>
{
    private readonly T _value1;
    private readonly T _value2;

    public Lerpable<T> (T value1, T value2)
    {
        _value1 = value1
        _value2 = value2
    }

    public T Lerp(float amount)
    {
        // Default behavior, I want to be able to change this depending on what T is.
        return amount > 0.5 ? _value2 : _value1;
    }
}

public class Lerpable<T>
{
    private readonly T _value1;
    private readonly T _value2;

    public Lerpable<T> (T value1, T value2)
    {
        _value1 = value1
        _value2 = value2
    }

    public T Lerp(float amount)
    {
        // Default behavior, I want to be able to change this depending on what T is.
        return amount > 0.5 ? _value2 : _value1;
    }
}

10 Replies

Jimmacle•2y ago

you'd have to compare typeof(T) to the types you're interested in what's the end goal? if you're only interested in numbers you can use the INumber<T> interface as a constraint

vanille.OP•2y ago

(Color is from Microsoft.Xna.Framework)

    public T Lerp(float amount)
    {
        if (typeof(T) == typeof(Color)) {
            return Color.Lerp(_value1, _value2, amount);
        }
        return amount > 0.5 ? _value2 : _value1;
    }

    public T Lerp(float amount)
    {
        if (typeof(T) == typeof(Color)) {
            return Color.Lerp(_value1, _value2, amount);
        }
        return amount > 0.5 ? _value2 : _value1;
    }

Can't, since if i have it inside of the function, the compiler won't be able to convert T into Color.

Jimmacle•2y ago

yeah that's about all you can do then, though you could also pattern match on _value1 or _value2 since you have those available e.g. if (_value1 is Color color1)

vanille.OP•2y ago

Still having a conversion issue, mainly with setting color1 to _value1.

Gruhlum•2y ago

sounds like a job for extensions.

public static class Extensions
{
    public static Color Lerp(this Color color)
    {
        return color;
    }
}

public static class Extensions
{
    public static Color Lerp(this Color color)
    {
        return color;
    }
}

vanille.OP•2y ago

Color.Lerp() is already a member of the class. ...I don't understand this answer.

Jimmacle•2y ago

you might have to do some sketchy unsafe things to force this pattern to work PepeHmmm

vanille.OP•2y ago

Jimmacle•2y ago

like Unsafe.As which is a type cast that ignores any safety checks

vanille.OP•2y ago

I'll just do it the original way I had planned, making inherited classes like LerpableColor : Lerpable<Color>. Thank you for the help though. mikuarigathanks

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Change function behavior depending on class' generic type.

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