Consider removing the constraint from ApiExtensions.Descendants about anglesharp HOT 3 CLOSED

Why don't you use Linq for that? There is a handy OfType<T>() method, which should be used for scenarios like this. IUrlUtilities does not carry any children, nor it is a logical part of a tree. It is just an interface that might be implemented in a node that is part of the tree.

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If I need to get all the descendants that implement an interface, of course, I can write node.Descendants<INode>.OfType<IFoo>, but what does Descendants need its type parameter for then? Just for the same purpose, doesn't it? So why do we need that constraint?

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Well, the constraint is not needed. But the implementation also just uses a LINQ-OfType<T> extension method. Nevertheless I see where this is going. The expressiveness in doing it in one step is really appealing.

The basic idea of the constraint was to give a hint what could be filtered (texts, elements, ...). But of course that rules out the scenario you'd like to have.

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