I would need something like Query.setParameter(int position, Object val)
for a Session.delete, but I can't find any method that "guesses the Hibernate type from the class of the given object" for the delete().
So I took a look at the code, and turned out that AbstractQueryImpl uses a SessionImplementor class, which has a lot of useful methods (for example you can call session.getFactory().getPersister(clazz)).

1) Is there a way to call session.delete if I don't know the Types of my args (without cast the session to the SessionImplementor class and use
its methods) ?

2) It seems to me that each "implementation" of interfaces of Hibernate is
coupled to a specific implementation of another one (example: AbstractQueryImpl uses a SessionImplementor class).
In this way, if you write another SessionImplementor class you won't be
able to use it in your AbstractQueryImpl .
What are interfaces good for if you don't use it?

(please don't take the second question as an accusation. I'm not a "great" programmer and I'm not fluent in English, so I couldn't find more
appriopriate words, but the meaning is not "you don't know how to program", the actual meaning is "please could you explain to me the logic").

1) No.

2) The internal interfaces in Hibernate represent "roles". Their purpose is to control and document dependencies, not necessarily to achieve polymorphism. In the case of SessionImplementor, it is also to allow for the possibility that the structure of the impl package may change, without requiring a change to the Type interface.

> 1) No.

Damn...

> 2) The internal interfaces in Hibernate represent "roles".

Could you point out some docs on this subjects?
Thanks for the super-fast answer!