如何避免从值类型的输出参数到接口的装箱？

Question

While developing I run into a question about boxing of the output parameter of value type when implementing an interface. How could I avoid boxing inside F method of IProvider interface from S[X] struct instance to IS interface ?

Any help would be greatly appreciated.

interface IProvider
{
    bool F(out IS value); 
}

class ConcreteProvider1 : IProvider
{
    public bool F(out IS value)
    {
        value = new S1(1); // boxing S1 to IS
        return true; // some logic here
    }
}

class ConcreteProvider2 : IProvider
{
    public bool F(out IS value)
    {
        value = new S2("text"); // boxing S2 to IS
        return true; // some logic here
    }
}

interface IS { }
readonly struct S1 : IS
{
    public int Value1 { get; }
    public S1(int value) => Value1 = value;
}

readonly struct S2 : IS
{
    public string Value2 { get; }
    public S2(string value) => Value2 = value;
}

class Program
{
    static void Main(string[] args)
    {
        var result = new IProvider[] { new ConcreteProvider1(), new ConcreteProvider2() }
                            .Any(p => p.F(out var value));
    }
}

Answer 1

Possibly I should use static method Try[X] with specific value type for the output parameter

readonly struct S2 : IS
{
    public string Value2 { get; }
    public S2(string value) => Value2 = value;

    public static bool TryParse(out S2 s2)
    {
        s2 = new S2("text");
        return true;
    }
}

and call static methods instead of using Linq

var result = S2.TryParse(out var s2) || S1.TryParse(out var s1);

PS All code in question and answer just sample to more simply describe the question