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c#arraysgenericscasting
mashinkata
mashinkata

Reputation: 75

Failing to cast to generic array

Hi I have the following extension method 

    public static T[] GetComponentsOfType<T>(this GameObject source) where T : MonoBehaviour
    {
        Component[] matchingComponents = source.GetComponents<Component>().Where(comp => comp is T).ToArray();
        T[] castedComponents = new T[matchingComponents.Length];
        for (int i = 0; i < matchingComponents.Length; i++)
        {
            castedComponents[i] = (T) matchingComponents[i];
        }
        return castedComponents;
    }

Which works completely fine however I tried to shorten it by just a single line

 return (T[]) source.GetComponents<Component>().OfType<T>().Cast<Component>().ToArray();

And apparently this line fails to cast the Component[] to T[] but when I cast each element separately it works (the first example). Why is that ?

Upvotes: 0

Views: 56

Answers (2)

Jeroen van Langen
Jeroen van Langen

Reputation: 22038

You should make use of the OfType<> only. In your solution, you are it back to Component, which can't be cast to T[], so thats the problem.

The OfType<> already casts it. It's like a substitute for Where(item => item is T).Cast<T>()

return source.GetComponents<Component>().OfType<T>().ToArray();

Upvotes: 2

Rafal
Rafal

Reputation: 12619

You can write:

source.GetComponents<Component>().OfType<T>().ToArray();

To do it in one line.

The cast fails because you are casting two types that do not match and Array of component to and array of T and that is invalid.

Upvotes: 2

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