get the iterator

[Marco]

I need to get a iterator from any generic collection.
public class .... GetIterator(Obj ect collection)
{

.....

}

How can I do this with reflection?

Thanks in advance.

[Tim Haughton]

"Marco" <te******@yahoo .com> wrote in message
news:11******** **************@ g44g2000cwa.goo glegroups.com.. .

I need to get a iterator from any generic collection.
public class .... GetIterator(Obj ect collection)
{

....

}

How can I do this with reflection?

I'm not sure I'm following you. Collections (meaning any class implementing
ICollection) implicitly implement IEnumerable. This means that you can call
GetEnumerator on them to get an enumerator (iterator). There's no need for
reflection.

If I've misunderstood feel free to post back.

--
Regards,

Tim Haughton

Agitek
http://agitek.co.uk
http://blogitek.com/timhaughton

[Oliver Sturm]

Marco wrote:

I need to get a iterator from any generic collection.
public class .... GetIterator(Obj ect collection)
{

....

}

How can I do this with reflection?

Why would you do this with reflection? If you know that the given type is
a collection and it has an iterator, you can just cast it to an
IEnumerable and get the iterator from there:

IEnumerable enumerable = collection as IEnumerable;
if (enumerable != null) {
// get the iterator from enumerable.GetE numerator()
// or just use it directly with foreach
}

Oliver Sturm
--
Expert programming and consulting services available
See http://www.sturmnet.org (try /blog as well)

[Tim Haughton]

"Oliver Sturm" <ol****@sturmne t.org> wrote in message
news:xn******** ********@msnews .microsoft.com. ..

Oliver Sturm
--
Expert programming and consulting services available
See http://www.sturmnet.org (try /blog as well)

Hi Oliver, I see your name's down for the nosh with Hugh MacLeod and chums
at December's London Geek dinner. I hope to make it myself - it will be nice
to put a face to the Usenet posts.

--
Regards,

Tim Haughton

Agitek
http://agitek.co.uk
http://blogitek.com/timhaughton

[Marco]

Thanks very much.I would like control tha collection implement
IEnumerable with reflection.

Can I put your code in a function and and return a IEnumerable or null?
How?

[Oliver Sturm]

Hi Tim,

Tim Haughton wrote:

Hi Oliver, I see your name's down for the nosh with Hugh MacLeod and chums
at December's London Geek dinner. I hope to make it myself - it will be
nice
to put a face to the Usenet posts.

Yes, that would be great. I haven't met most of the guys (and girls!) yet
myself, so I'm looking forward to that. Hope you can make it!
Oliver Sturm
--
Expert programming and consulting services available
See http://www.sturmnet.org (try /blog as well)

[Oliver Sturm]

Marco wrote:

Thanks very much.I would like control tha collection implement
IEnumerable with reflection.
I'm sorry, I don't understand exactly what you want to do with Reflection.
Can I put your code in a function and and return a IEnumerable or null?
How?

The magic of the "as" operator makes that extremely easy:

IEnumerable GetIEnumerable( object potentialCollec tion) {
return potentialCollec tion as IEnumerable;
}
Oliver Sturm
--
Expert programming and consulting services available
See http://www.sturmnet.org (try /blog as well)

[Marco]

it's right.
Thanks very much.
I would like control that collection implement IEnumerable with
reflection but it's a wrong way.

[Helge Jensen]

Oliver Sturm wrote:

IEnumerable enumerable = collection as IEnumerable;
if (enumerable != null) {
// get the iterator from enumerable.GetE numerator()
// or just use it directly with foreach
}

Why use "collection as IEnumerable"? If it's supposed to be a collection
just use a cast. What would be a reasonable behaviour if collection is
not IEnumerable?

I'd write:

IEnumerator it = ((IEnumerable)c ollection).GetE numerator();

or for iteration:

foreach ( Foo foo in ((IEnumerable)c ollection )
...

--
Helge Jensen
mailto:he****** ****@slog.dk
sip:he********* *@slog.dk
-=> Sebastian cover-music: http://ungdomshus.nu <=-

[Oliver Sturm]

Helge Jensen wrote:

Why use "collection as IEnumerable"? If it's supposed to be a collection
just use a cast. What would be a reasonable behaviour if collection is not
IEnumerable?

I'd write:

IEnumerator it = ((IEnumerable)c ollection).GetE numerator();

or for iteration:

foreach ( Foo foo in ((IEnumerable)c ollection )
...

Well, the way the sample code is given (and requested by the OP) there
wasn't really any guarantee that the object would be a collection. In that
case the cast might be unsafe, that's why I'm using "as". The whole method
the OP was posting about would be kind of pointless if it had a parameter
of a collection type to start with, wouldn't it? :-)

And it's better to use

IEnumerable enumerable = collection as IEnumerable;
if (enumerable != null)
...

than

if (collection is IEnumerable) {
IEnumerable enumerable = (IEnumerable) collection;
...
}

because with the "as" operator, you get to check for the correct type and
acquire the interface at the same time. I usually use casts only if either
I'm completely sure that the target type is available or if, for some
reason, I want to assert that the target type *must* be available at the
point.
Oliver Sturm
--
Expert programming and consulting services available
See http://www.sturmnet.org (try /blog as well)