Creating a generic class instance from a type parameter

Question

5.00/5 (1 vote)

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Say we have a class like this :

C#

public class someclass<T> : Iinterface {}

And we have a function like this:

C#

public Iinterface Create(Type type)
{
// how to return ?
}

How can we return an instance of the someclass based on a parameter say typeof(int) in the Create method without ugly "if then" or "switch" statements?

Posted 15-Feb-12 22:43pm

Mehdi Gholam

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3 solutions

Solution 1

see this:
Generics in C# 2.0[^]

Posted 15-Feb-12 22:50pm

CRDave1988

Solution 2

Reflection allows you to create objects dynamically:

C#

string myType = "MyNamespace.MyClass";
Assembly asm = Assembly.GetExecutingAssembly();
Type t = asm.GetType(myType);
Object o = Activator.CreateInstance(t, null, null);

So in your case, you would need just the last line.

Posted 15-Feb-12 22:50pm

OriginalGriff

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BobJanova · Accepted Answer · 2012-02-15T23:37:00

Solution 3

Type finalType = typeof(someclass<>);
return Activator.CreateInstance(finalType.MakeGenericType(type));

See also this blog[^] which a Google search turned up.

Posted 15-Feb-12 23:37pm

BobJanova

Comments

Mehdi Gholam 16-Feb-12 6:02am

Great it works! I had to pass args to the ctor but that's ok.

My 5!