Type polymorphism and type variance

[Ali Çehreli]

On 12/06/2012 12:08 PM, js.mdnq wrote:
 > On Thursday, 6 December 2012 at 03:22:55 UTC, Ali Çehreli wrote:

The following comment is relevant:

 >> /* Although this can be a polymorphic type, I am assuming that all of
 >> the edge
 >> * handlers will produce the same type of result. */
 >> struct HandlingResult
 >> {}

 > Remember though, the return type of the functions have to match the node
 > type they are associated with.

If HandlingResult is an interface, then the Edge functions can all 
return a descendent of that interface. (In OOP speak, edgeHandler() 
functions would have "covariant return types".)

Ali