My name
is
Jon Skeet

Generic type function (property)

I'm trying to return a T type value.

public T this[int index]
{
     get
     {
           if (typeof(T) == typeof(int))
              return (T) dynEx[index].Int;
           else if (typeof(T) == typeof(string))
              return (T) dynEx[index].Str;
     }
}

dynEx is a complex object that returns an object based on some custom expression.

The code above obviously doesn't work because it has an error: "cannot convert type 'int' to T" and "cannot convert type 'string' to T".

How can I achieve this without having a performance impact?

This property is called more than a thousand times per frame (it's a game).

In order to cast to int, you'll need to cast the result to object first, potentially boxing. It's annoying, but unfortunately it's a limitation of C# generics - for good reasons that escape me right now, unfortunately. So you want:

public T this[int index]
{
    get
    {
        if (typeof(T) == typeof(int))
        {
            return (T) (object) dynEx[index].Int;
        }
        else if (typeof(T) == typeof(string))
        {
            return (T) (object) dynEx[index].Str;
        }
        // TODO: Whatever you want to happen if T isn't int/string
    }
}

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