(a) The donee of a power of appointment which is not presently
exercisable, or of a postponed power which has not become exercisable,
cannot contract to make an appointment; except that this prohibition
shall not apply if the donor and donee are the same person. Such a
prohibited contract, if made, cannot be the basis of an action for
specific performance or damages, but the promisee can obtain restitution
of the value given by him for the promise unless the donee has exercised
the power pursuant to the contract.
(b) The provisions of this section shall not abridge the ability of
the donee of a power of appointment which is not presently exercisable
to release his power pursuant to 10-9.2 or to make the power, after
release, an imperative power, except that where the donor designated
persons or a class to take in default of the donee's exercise of the
power, a release with respect to appointive property must serve to
benefit all those so designated as provided by the donor.