CODEWITHSUNDEEP
c#genericsreflection
bluee
bluee

Reputation: 1027

How do you call a generic method if you only know the type parameter at runtime?

I have this method:

public List<T> SomeMethod<T>( params ) where T : new()

So I want to call this SomeMethod which is fine if I know the type:

SomeMethod<Class1>();

But if I only have Class1 at runtime I'm unable to call it?

So how to call SomeMethod with unknown T type? I got Type by using reflection.

I have the Type of type but SomeMethod<Type | GetType()> doesn't work.

Update 7. May:

Here is a sample code of what I want to achieve:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;

namespace ConsoleApplication63
{
    public class DummyClass
    {
    }

    public class Class1
    {
        public string Name;
    }

    class AssemblyTypesReflection
    {
        static void Main(string[] args)
        {
            object obj = new Class1() { Name = "John" } ;

            Assembly assembly = Assembly.GetExecutingAssembly();
            var AsmClass1 = (from i in assembly.GetTypes() where i.Name == "Class1" select i).FirstOrDefault();


            var list = SomeMethod<AsmClass1>((AsmClass1)obj); //Here it fails
        }

        static List<T> SomeMethod<T>(T obj) where T : new()
        {
            return new List<T> { obj };
        }
    }
}

This is a demo taken out of a bigger context.

Upvotes: 9

Views: 7077

Answers (2)

nawfal
nawfal

Reputation: 73173

You can make use of dynamic keyword in C# 4. You require .NET 4.0 or above as well.:

SomeMethod((dynamic)obj);

The runtime infers the actual type argument and makes the call. It fails if obj is null since then there is no type information left. null in C# has no type.

Upvotes: 5

SLaks
SLaks

Reputation: 887453

You need to call it using reflection:

var method = typeof(SomeClass).GetMethod("SomeMethod");
method.MakeGenericMethod(someType).Invoke(...);

Upvotes: 8

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