Generics, constrains and inheritance

  • Thread starter Thread starter Joe
  • Start date Start date
J

Joe

Hi All!

Here's the problem I'm having. I want to create a generic class that
inherits from CollectionBase and implements IBindingList. As part of
IBindingList I have to implement AddNew(). Since this is a generic class the
new throws an error "Cannot create an instance of the variable type 'T'
because it does not have the new constraint".

How do I add a constraint to my class and be able to keep the CollectionBase
and IBindingList?

When I add the where <T>: it means that I want the class T to implement
CollectionBase and IBindingList.

Is it possible to do what I want?

Thanks,
Joe
 
I believe I have my answer. I need to declare my class like this:

class MyClass<T> : CollectionBase, IBindingList where T: new ()
{
....
}
 
I believe I have my answer. I need to declare my class like this:

class MyClass<T> : CollectionBase, IBindingList where T: new ()
{
    ....

}
Click to expand...
I don't think compiler knows what t where T: new () means...
 
puzzlecracker said:
I should have rtfm'ed. I didn't know that you can constrain types
based on different constructor types... learn something new every
day...
Click to expand...

You can't. At least not the part about different constructor types. There
is a constraint for "public parameterless constructor" and that's it, sadly.
 
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