How to determine base interface???

[J. Jones]

Suppose the following:

class MyContainer : System.Collecti ons.CollectionB ase
{
//...
}

(where CollectionBase implements IList, ICollection)

How do I determine if a type (such as MyContainer) derives from IList?

System.Type type = typeof(MyContai ner);

type is IList -> false

type.IsSubclass Of(typeof(IList )) -> false

type.IsAssignab leFrom(typeof(I List)) -> false

etc., all tests return false.

So, what I need is a way to determine if a particular type derives from IList,
no matter how far up the hierarchy it is.

Thanks

[Jon Skeet [C# MVP]]

J. Jones <[e-mail] m> wrote:

Suppose the following:

class MyContainer : System.Collecti ons.CollectionB ase
{
//...
}

(where CollectionBase implements IList, ICollection)

How do I determine if a type (such as MyContainer) derives from IList?

System.Type type = typeof(MyContai ner);

type is IList -> false

type.IsSubclass Of(typeof(IList )) -> false

type.IsAssignab leFrom(typeof(I List)) -> false

etc., all tests return false.

So, what I need is a way to determine if a particular type derives from IList,
no matter how far up the hierarchy it is.

You're using IsAssignableFro m the wrong way round - it's very easy to
do, and I always have to look up the documentation to check it.
Basically, you want

typeof(IList).I sAssignableFrom (type)

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Anders Norås [MCAD]]

J. Jones wrote:

No go. I need to test a System.Type variable, so your code becomes

Ops. My mistake, I read the question a bit too fast and though
MyContainer was a variable. If MyContainer is a class you can do this.

if (typeof(MyConta iner).GetInterf ace(typeof(ILis t).FullName)) {
// MyContainer implements IList.
} else {
// MyContainer does not implement IList.
}

Anders Norås
http://dotnetjunkies.com/weblog/anoras/

[Joakim Karlsson]

Zoury wrote:

Console.WriteLi ne("MyContaine r implements IEnumerable : {0}",
typeof(MyContai ner).GetInterfa ce("System.Coll ections.IEnumer able") != null)

Doh! Of course that how it is done! For some reason I got into my head
that Type.GetInterfa ce() would throw an exception if the requested
interface wasn't implemented.

Time to log off I guess! :)

Thanks Zoury!

/Joakim

[Zoury]

> but i've noticed though that you misread the help file, since the

BaseCollection *does not* implements the Ilist :

man... it's for me to take off.
you were talking about CollectionBase and not BaseCollection. ...

anyway the sample pattern works properly. But as shown by Mattias,
IsAssignableFro m() seems to be the proper way to do it.

have a nice weekend !
i know will :O)

--
Best Regards
Yanick

[J. Jones]

Jon Skeet [C# MVP] wrote:

J. Jones <[e-mail] m> wrote:

Suppose the following:

class MyContainer : System.Collecti ons.CollectionB ase
{
//...
}

(where CollectionBase implements IList, ICollection)

How do I determine if a type (such as MyContainer) derives from IList?

System.Type type = typeof(MyContai ner);

type is IList -> false

type.IsSubcla ssOf(typeof(ILi st)) -> false

type.IsAssign ableFrom(typeof (IList)) -> false

etc., all tests return false.

So, what I need is a way to determine if a particular type derives from IList,
no matter how far up the hierarchy it is.

You're using IsAssignableFro m the wrong way round - it's very easy to
do, and I always have to look up the documentation to check it.
Basically, you want

typeof(IList).I sAssignableFrom (type)

Check! Switched, worked as desired.

Thanks.