Question

Just wondering if there is anyway to represent the following code in C# 3.5:

public struct Foo<T> {

    public Foo(T item) {
        this.Item = item;
    }

    public T Item { get; set; }

    public static explicit operator Foo<U> ( Foo<T> a )
        where U : T {

        return new Foo<U>((U)a.Item)
    }
}

Thanks

Answer 1

Conversion operators can’t be generic. From the spec section 10.10, here’s the format of a conversion-operator-declarator:

conversion-operator-declarator:
    implicit   operator   type   (   type   identifier   )
    explicit   operator   type   (   type   identifier   )

Compare this with, say, a method-header:

method-header:
attributes_opt method-modifiers_opt partial_opt return-type
member-name type-parameter-list_opt ( formal-parameter-list_opt )
type-parameter-constraints-clauses_opt

(Sorry about the formatting – not sure how to do it better.)

Note that the operator format doesn’t include a type parameter list or type parameter constraints.