Is there a way to initialize an object from a reference class in C#? [duplicate]

Question

In Delphi, when i want to create an object from uncertain derived class, i was using class of statement;

TShape = class
public
  procedure Draw;
end;

TCircle = class(TShape)
public
  procedure Draw;
end;

TShapeClassRef = class of TShape;

and i was creating object as;

var
  ref:TShapeClassRef;
  drawing:TShape;
begin
  ref:=TCircle;
  drawing:=ref.Create;
  drawing.draw; //this is a circle object, and it draws circle
end;

I couldn't find anything like that in c#.

Are you looking for something like Activator.CreateInstance(yourTypeGoesHere)? — DerApe
– DerApe, Commented Jul 8, 2015 at 6:39
C# does not have metaclasses. So no direct analog. Yes you can use reflection but I really don't like that. I personally think the best way is as I wrote in an answer at the linked dupe: And yet another option is to replace your dictionary of classes with a dictionary of delegates that return a new instance of your object. With lambda syntax that option yields very clean code. — David Heffernan
– David Heffernan, Commented Jul 8, 2015 at 7:11

Salah Akbari · Accepted Answer · 2015-07-08 13:43:10Z

3

Use Type like this:

public class TShape { }

And:

Type t = typeof(TShape);

To initialize an object through t variable, use Activator.CreateInstance(t):

Shape shp = (Shape)Activator.CreateInstance(t);

edited Jul 8, 2015 at 13:43

answered Jul 8, 2015 at 6:43

Salah Akbari

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4 Comments

Ibrahim Ozdemir Over a year ago

that's just the half of my question, how should i initialize an object through "t" variable Type t = typeof(TCircle); Shape shp = new t(); ?

Salah Akbari Over a year ago

Like this: Shape shp = (Shape)Activator.CreateInstance(t); see my Updated answer.

Ibrahim Ozdemir Over a year ago

thank you so much, you've been realy helpfull :)

cja Over a year ago

How to pass parameters to the constructor?

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