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

[Zoury]

Hi!

how about that ? is that too much overkill ?
//***
IList lst = type as IList;
if (lst != null)
Console.WriteLi ne("type does implement IList");
//***

--
Best Regards
Yanick
"J. Jones" <[e-mail] m> a écrit dans le message de
news:e2******** ******@TK2MSFTN GP14.phx.gbl...

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

[Anders Norås [MCAD]]

J. Jones wrote:

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

Use the C# is statement:
if (MyContainer is IList) {
// Handle IList implementation
}

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

[J. Jones]

Zoury wrote:

Hi!

how about that ? is that too much overkill ?
?!
//***
IList lst = type as IList;
if (lst != null)
Console.WriteLi ne("type does implement IList");
//***

No go. IList isn't a type, but a class (interface). You can't convert a type
to an instance, what is would happen if permissible in your code.

[J. Jones]

Anders Norås [MCAD] wrote:

J. Jones wrote:

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

Use the C# is statement:
if (MyContainer is IList) {
// Handle IList implementation
}

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

if (typeof(MyConta iner) is IList)

which is false.

Thanks

[Joakim Karlsson]

Anders Norås [MCAD] wrote:

J. Jones wrote:

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

Use the C# is statement:
if (MyContainer is IList) {
// Handle IList implementation
}

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

MyContainer is a class, not a variable, so that won't compile.

This is ugly, but it works:

using System;

interface IWhatever {}

public class App : IWhatever
{
public static void Main()
{
bool implementsIFace =
ImplementsIFace (typeof(IClonea ble), typeof(App));
}

static bool ImplementsIFace (Type interfaceType, Type implementingTyp e)
{
Type[] interfaces = implementingTyp e.GetInterfaces ();
foreach(Type t in interfaces)
{
if(t == interfaceType) return true;
}
return false;
}
}

/Joakim

[Zoury]

oh sorry i did misread your sample.

but i've noticed though that you misread the help file, since the
BaseCollection *does not* implements the Ilist :
---
Public Class BaseCollection
Inherits MarshalByRefObj ect
Implements ICollection, IEnumerable
---

so here's how you could test it (without any loop) (not tested) :
'***
Console.WriteLi ne("MyContaine r implements IEnumerable : {0}",
typeof(MyContai ner).GetInterfa ce("System.Coll ections.IEnumer able") != null)
'***

--
Best Regards
Yanick

[Jon Skeet [C# MVP]]

"Anders Norås [MCAD]" <an**********@o bjectware.no> wrote:

J. Jones wrote:

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

Use the C# is statement:
if (MyContainer is IList) {
// Handle IList implementation
}

I believe (given the rest of the post) that the OP is trying to get
that information from the Type reference, not an instance of the type.

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

[Jon Skeet [C# MVP]]

<"Zoury" <yanick_lefebvr e at hotmail dot com>> wrote:

how about that ? is that too much overkill ?
//***
IList lst = type as IList;
if (lst != null)
Console.WriteLi ne("type does implement IList");
//***

It still won't work, for the same reason that "type is IList" won't
work - the Type type itself doesn't implement IList.

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

[Mattias Sjögren]

type.IsAssigna bleFrom(typeof( IList)) -> false

Close, but backwards. Try

typeof(IList).I sAssignableFrom (type)


Mattias

--
Mattias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.