我可以忽略C#接口中的泛型类型吗？

interface I<T>
{
    //The generic type parameter U is independent of T.
    //Notice how F "forwards" the type U from input to output.
    Tuple<T,U> F<U>(U u);
}

考虑以下玩具类：

class C : I<char>
{
    public char Value { get; set; }
    public Tuple<char,U> F<U>(U u)
    {
        return Tuple.Create(Value,u);
    }
}

以下是一些示例用法：

I<char> instance = new C { Value = '!' };
Tuple<char,int> x = instance.F(5); // ('!',5)
Tuple<char,string> y = instance.F("apple"); // ('!',"apple")

更新

• I allow users to create an EqualitySieve<ABusinessObject>().ForProperty(x=>x.AnInt).
• This actually returns an EqualitySieve<ABusinessObject,int> to the user,but since it’s a fluent interface I remove them from having to care about that part.
• I would like EqualitySieve,LessThanSieve,etc. to implement ISieve<ABusinessObject>.

使用我上面提到的想法,你可以做你想要的(我想).

interface ISieve<T>
{
    //It's still not clear what you actually want in this interface...
}

static class Sieve
{
    public EqualitySieve<T> Equality<T>()
    {
        return new EqualitySieve<T>();
    }

    public LessThanSieve<T> LessThan<T>()
    {
        ...
    }
}    

class EqualitySieve<T> : ISieve<T>
{
    //Notice how the property type P is independent of T
    //and can be inferred here from the passed expression
    public EqualitySieve<T,P> ForProperty<P>(
        Expression<Func<T,P>> propertyExpression)
    {
        return new EqualitySieve<T,P>
        {
            PropertyExpression = propertyExpression
        };
    }
}

class EqualitySieve<T,P> : ISieve<T>
{
    public Expression<Func<T,P>> PropertyExpression { get; set; }
}

用法：

//Assuming MyObject.MyProperty is an int property
//s has type EqualitySieve<MyObject,int>
var s = Sieve.Equality<MyObject>().ForProperty(x => x.MyProperty);