How to check if CLASS implements an interface?

[Joe Rattz]

Ok, I am trying to figure out how to tell if a class (not object) implements
a particular interface. Using the "is" operator does not seem to work for
me and I assume its because I have a class, not an object I am wanting to
check.

Here's my scenario. I am dynamically loading assemblies (dlls) at runtime.
I am getting the list of types from each assembly, and if that type
implements a particular interface, then and only then do I want to
instantiate one. I have seen several articles showing how to do the dynamic
loading, but I haven't seen anyone address this issue. Perhaps in a given
assembly, there are helper types that do not implement the interface and I
wouldn't want to instantiate one of them. How can I verify that a type
(System.Type) implements a particular interface?

Thanks.

[Michael C]

IsAssignableFrom

"Joe Rattz" <jo******@yahoo.com> wrote in message
news:OK**************@TK2MSFTNGP15.phx.gbl...

Ok, I am trying to figure out how to tell if a class (not object)
implements
a particular interface. Using the "is" operator does not seem to work for
me and I assume its because I have a class, not an object I am wanting to
check.

Here's my scenario. I am dynamically loading assemblies (dlls) at
runtime.
I am getting the list of types from each assembly, and if that type
implements a particular interface, then and only then do I want to
instantiate one. I have seen several articles showing how to do the
dynamic
loading, but I haven't seen anyone address this issue. Perhaps in a given
assembly, there are helper types that do not implement the interface and I
wouldn't want to instantiate one of them. How can I verify that a type
(System.Type) implements a particular interface?

Thanks.

[Bjorn Abelli]

"Joe Rattz" <jo******@yahoo.com> wrote...

How can I verify that a type
(System.Type) implements a particular interface?

If you have a Type instance (e.g. "t"), you can use:

Type t2 = t.GetInterface("ITheInterface");

If t2 is not null, then t implements ITheInterface.

// Bjorn A

[Zoury]

Hi Joe!

You can use the "as" operator and test the result :
//***
ArrayList al = new ArrayList();
IEnumerable interf = al as IEnumerable;
if (interf == null)
Console.WriteLine("ArrayList doesn't implement IEnumerable");
else
Console.WriteLine("ArrayList implements IEnumerable");
//***

--
Best Regards
Yanick

[Joe Rattz]

Thanks for the input. I initially could not get this to work. It felt like
it worked backwords from what I needed, and I couldn't call IsAssignableFrom
on the interface. Since I did get Bjorn's idea to work, I initially coded it
that way. I was typing my response to your post (this response) to tell you
it wasn't working when an idea came to me. So, I used the typeof operator
on the interface and that worked. My code ended up looking like:

if(typeof(IMyInterface).IsAssignableFrom(type))
{
// instantiate an object from this type.
}

That works just fine and I prefer the code this way.

Thanks.
"Michael C" <mc*****@NOSPAMoptushome.com.au> wrote in message
news:uV**************@TK2MSFTNGP14.phx.gbl...

IsAssignableFrom

"Joe Rattz" <jo******@yahoo.com> wrote in message
news:OK**************@TK2MSFTNGP15.phx.gbl...

Ok, I am trying to figure out how to tell if a class (not object)
implements
a particular interface. Using the "is" operator does not seem to work for me and I assume its because I have a class, not an object I am wanting to check.

Here's my scenario. I am dynamically loading assemblies (dlls) at
runtime.
I am getting the list of types from each assembly, and if that type
implements a particular interface, then and only then do I want to
instantiate one. I have seen several articles showing how to do the
dynamic
loading, but I haven't seen anyone address this issue. Perhaps in a given assembly, there are helper types that do not implement the interface and I wouldn't want to instantiate one of them. How can I verify that a type
(System.Type) implements a particular interface?

Thanks.

[Joe Rattz]

Thanks Bjorn, that works perfect. I did code this and it did what I needed.
Ultimately though, I preferred the code to use the approach that Michael C
mentioned. Some might want to look at my response to see how this worked.

Here is what my code looked like using your approach, and it worked just
fine:

Type t = type.GetInterface("IMyInterface");
if(t != null)
{
// Instante a type object.
}

Thanks.

"Bjorn Abelli" <bj**********@DoNotSpam.hotmail.com> wrote in message
news:%2****************@TK2MSFTNGP15.phx.gbl...

"Joe Rattz" <jo******@yahoo.com> wrote...

How can I verify that a type
(System.Type) implements a particular interface?

If you have a Type instance (e.g. "t"), you can use:

Type t2 = t.GetInterface("ITheInterface");

If t2 is not null, then t implements ITheInterface.

// Bjorn A