How to use typeof or GetType() as Generic's Template?

typeof generic typescript
c# typeof generic type
c# reflection get generic type
generic type get type
c# create instance of generic type at runtime
use variable as type c#
c# create instance of generic type with parameters
c# instantiate generic type

If it's harder to explain using words, let's look at an example I have a generic function like this

void FunctionA<T>() where T : Form, new()
{
}

If I have a reflected type, how do I use it with the above function? I'm looking forward to do this

Type a = Type.GetType("System.Windows.Forms.Form");
FunctionA<a>();

Of cause the above method doesn't work.

You can't. Generics in .NET must be resolved at compile time. You're trying to do something that would resolve them at runtime.

The only thing you can do is to provide an overload for FunctionA that takes a type object.


Hmmm... the commenter is right.

class Program
{
    static void Main(string[] args)
    {
        var t = typeof(Foo);
        var m = t.GetMethod("Bar");
        var hurr = m.MakeGenericMethod(typeof(string));
        var foo = new Foo();
        hurr.Invoke(foo, new string[]{"lol"});
        Console.ReadLine();
    }
}

public class Foo
{
    public void Bar<T>(T instance)
    {
        Console.WriteLine("called " + instance);
    }
}

MakeGenericMethod.

How to get the type of T from a member of a generic class or method , GetGenericArguments() You can use this one for return type of generic list: GetType(); if (type == null) return; if (type != typeof(account)) //account is listitem in � ' Use the GetType operator to create the generic type ' definition directly. To specify the generic type definition, ' omit the type arguments but retain the comma that separates ' them. Dim d1 As Type = GetType(Dictionary(Of ,)) ' You can also obtain the generic type definition from a ' constructed class.

class Program
{
    static void Main(string[] args)
    {
        int s = 38;


        var t = typeof(Foo);
        var m = t.GetMethod("Bar");
        var g = m.MakeGenericMethod(s.GetType());
        var foo = new Foo();
        g.Invoke(foo, null);
        Console.ReadLine();
    }
}

public class Foo
{
    public void Bar<T>()
    {
        Console.WriteLine(typeof(T).ToString());
    }
}

it works dynamicaly and s can be of any type

How to: Examine and Instantiate Generic Types with Reflection , GetType(String) method overload with a string describing the type, and by Use the typeof operator to create the generic type // definition directly. ITestArgument, new() {} // Define a class that meets the constraints on the� Console.WriteLine(typeof(Dictionary<,>)); // Output: // System.Collections.Generic.Dictionary`2[TKey,TValue] An expression cannot be an argument of the typeof operator. To get the System.Type instance for the runtime type of an expression result, use the Object.GetType method. Type testing with the typeof operator. Use the typeof operator to

A few years late and from a msdn blog, but this might help:

Type t = typeof(Customer);  
IList list = (IList)Activator.CreateInstance((typeof(List<>).MakeGenericType(t)));  
Console.WriteLine(list.GetType().FullName); 

typeof Operator Keyword in C#, It is allowed to use typeof operator on open generic types. static void Main() Difference between typeof operator and GetType method� You can also load an assembly using the Assembly.Load method, and then use the Assembly.GetType or Assembly.GetTypes method to get Type objects. If a type is in an assembly known to your program at compile time, it is more efficient to use typeof in C# or the GetType operator in Visual Basic. GetType only works on assemblies loaded from disk.

I solved this problem in a different way. I have a list class that encapsulates the (real) Dapper functionality. It inherits from a base class that is the dummy class for mocking. Every method in the base class is overridden by the real class. Then I don't need to do anything special. If in the future, I want to do something special with SQLite or a home-grown in-memory database, I can always add that to the base class later if I wish.

typeof(TSecret), NET interop IL stub also use secret argument to support sharing interop “stubs” NET runtime supports 3 kinds of generic lookup for typeof(T) case: Case #1: Generic class, non-generic method class T1<T> { public void Func() { Console. JIT_GetRuntimeType (00007fff`64abe8f0) ; Get Type object. typeof Operator GetType Method; It takes the Type itself as an argument and returns the marked type of the argument. It only invoked on the instance of the type. It is used to get a type that is known at compile-time. It is used to obtain the type of an object at run-time. It cannot be used on an instance. It can be used on instance.

Using .NET Generics with a type derived at runtime – The Reformed , How to create an instance of a generic type where the type is defined at runtime. The two Only interested in how to use Generics with a runtime-derived type? var dataType = new Type [] { typeof ( string )}; GetType(). Unfortunately, c# typeof operator doesn't work on generics as shown bellow. Actually, it's quite fortunate that it doesn't work as you expect it to work.

type(of:), You can use the type(of:) function to find the dynamic type of a value, smileyType.text) } let emojiSmiley = EmojiSmiley() printSmileyInfo(emojiSmiley) // Smile! In a case like this, where a generic parameter T is bound to a protocol P , the� C# enums don't store types, the specific enum is a type, each instantiation of that enum has a value. If you want to use an enum to create a type from then you should just use a factory and hard code it to new up your types. – Spence Aug 22 '12 at 0:17

Surprise! Creating an instance of an open generic type, WriteLine(x.GetType().GetTypeInfo().IsGenericTypeDefinition);. That just shouldn' t happen. You shouldn't be able to create� Code sample shows use of C# typeof operator and Type.GetType() method. In C#, types are inherited from the System.Type. The C# typeof operator get the System.Type of a type.

Comments
  • How can .NET get so close to the power of a 1958 technology and yet still be so far away?
  • .NET is mainstream, Lisp (I assume that's what your reference is to) is not. That may answer the "why" question.
  • That's one very definitive answer. Too bad it's incorrect. You can, through reflection, invoke generic methods using generic arguments resolved at runtime. It's not always desired, and one may wonder why he has to do it before actually using it, but it's possible.