C#: Generic Parameter vs Object type parameter

Question

I have two overloaded methods one is expecting object type parameter and other generic params list. I'm trying to understand that when which function will be called. I'm passing string object and it's calling generic params method.

class Program
{
    static void Main(string[] args)
    {
        string s = "string";
        Invoke(s);
        Console.ReadLine();
    }

    static void Invoke(object s)
    {
        Console.WriteLine("Object param invoked");
    }

    static void Invoke<T>(params T[] values)
    {
        Console.WriteLine("Params method invoked");
    }
}

It's giving output as: 'Params method invoked'.

But I'm not sure why always this method called.I also tried with passing int parameter but again params method invoked. Please if anyone can explain this for me. Thanks.

When checking the overloads the most strict one is called first, in this case `Invoke(string value)` is checked first and called. — Cleptus, Dec 19 '18 at 19:15
@bradbury9 In this scenario when will object parameter method be called? — Rana Mujahid, Dec 19 '18 at 19:24
Can I say when i pass string object to method compiler read it as Invoke and now parameter type becomes string? String is more specific than object. So Params method invoked. Am I right? — Rana Mujahid, Dec 19 '18 at 20:04

score 5 · Answer 1 · answered Dec 19 '18 at 19:12

5

In short, type T is more specific than Object because Invoke<string> is a valid invocation.

answered Dec 19 '18 at 19:12

madreflection

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2

To add on to this answer, the compiler can infer the type argument; which is why OP didn't need to write `Invoke(s);`. See the [generics documentation](https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/generics/generic-methods). – Lews Therin Dec 19 '18 at 19:14

C#: Generic Parameter vs Object type parameter

1 Answers1