Testing if an object implements an interface

[Steve B.]

Hello

I'm trying to test if an object is an instance of a class that implements a
specific interface.

I use this code :

if(!(f.GetType().IsSubclassOf(typeof(IParametrableForm))))

throw new SystemException("The form is not parametrable");

The exception is always thrown, instead the tested object actually implement
the interface :

public class frmProduct : System.Windows.Forms.Form, IParametrableForm

{

....



What's wrong with my code ?

Thanks,
Steve

 

[Daniel Moth]

That is because it is not a subclass of the interface. Deriving from a class
and implementing an interface are two different things.

One way to achieve what you want is to call to GetInterfaces and check if
IParametrableForm is in there.

Cheers
Daniel

 

[Steve B.]

Thanks for the answer

A little bit more easy way to reach my goal is this one:

if((f as IParametrableForm) == null)
throw new ....

Thanks anyway

 

[Guest]

You can also do :

if(typeof(IParametrableForm).IsAssignableFrom(f))
{
....Do whatever
}