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57

answers:

1

I need to create a generic type, but I do not know the type at compile time. I would like to do this:

Type t = typeof(whatever);
var list = new List<t>

this won't compile, because t is not a valid type. But it does know all about a valid type. Is there a way to dynamically create the generic list from a System.Type like this? I may need reflection, and that's ok, I am just a bit lost here.

+9  A: 

Like this:

Type t;
Type genericListType = typeof(List<>).MakeGenericType(t);
object list = Activator.CreateInstance(genericListType);

Note that you can only assign it to a variable of type object. (Although you can cast to to the non-generic IList interface)

To use the list variable, you'll probably need reflection.

SLaks
+1 Didn't know `List<>` was legal at all. pretty cool.
Igor Zevaka
@Igot: Only in `typeof`.
SLaks
This works great, except it is a pain to use afterward. Gets the job done though.
CaptnCraig
Correct; it's a pain to use. There may be better options; you can ask another question here and tell us what you're trying to do.
SLaks
Turns out in my application of this, I can quite easily cast it to a nongeneric interface and it works quite well.
CaptnCraig