(a) The provisions of this title shall govern the construction of and punishment for any offense defined in this title and committed after 12:01 A.M. January 1, 1980, as well as the construction and application of any defense to a prosecution for such an offense.
(b) Unless otherwise expressly provided or unless the context otherwise requires, the provisions of this chapter shall govern the construction of and punishment for any offense defined outside this title and committed after the effective date thereof, as well as the construction and application of any defense to a prosecution for such an offense.
(c) The provisions of this title do not apply to or govern the construction of and punishment for any offense committed prior to 12:01 A.M. January 1, 1980, or the construction and application of any defense to a prosecution of such an offense. Such an offense must be construed and punished according to the provisions of law existing at the time of the commission thereof in the same manner as if this title had not been enacted.