117. Effect on gift subject to exercise of power.

A gift to take effect on the determination of prior interests, including interests to be appointed under a power, may take effect as an independent alternative gift. If the power is not exercised, or is exercised so as to render the subsequent gift unobjectionable under the rule, the gift takes effect; and, if it is exercised so as to make the subsequent gift objectionable under the rule, the gift will be void, so that until the exercise of the power it cannot be said whether the gift is good or bad1. In relation to dispositions under instruments taking effect