Dear mpaine,

Yes, you can do that by the Find method of the generic list, and a
specific predicate.

The Find method searches for an element that matches the conditions
defined by the specified predicate.
The Predicate is a delegate to a method that returns true if the
object passed to it matches the conditions defined in the delegate.The
elements of the current List are individually passed to the Predicate
delegate, moving forward in the List, starting with the first element
and ending with the last element. Processing is stopped when a match
is found.

Since the search is linear it's an O(n) operation where n is the
number of elements in the list.

If you need faster search capabilities, try using other data
structures (such as Hashtable (O(1)) - to solve the hashcode problem,
just derive from the class that would be the key and make sure to
return the same hashcode for objects that are equal, or Dictionary
(O(1)) with specified comparer).

Hope this helps,
Moty.

Hi Mpaine,

List(Of T) doesn't support the function you want. The reason is as what you
have said--different object instances have different hash code.

Dictionary(Of TKey, TValue) should meet your requirement.

I thought a possible workaround is to derive a new type from List<T>  and
override the Contains method. Unfortunately, the Contains method isn't
overridable. So it seems it is impossible to get the List(Of T) to support
the function you want.

Hope this helps.
If you have any question, please feel free to let me know.

Sincerely,
Linda Liu
Microsoft Online Community Support

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This is all helpful, thank you everyone!

just as a friendly followup, I found the easiest solution for my needs -- use
structures instead of classes, they automatically compare the internal data
for equals on their hashcodes.