Section 5.05. Application of chapter to offenses committed before and after enactment

1. The provisions of this chapter shall govern the construction of and
  punishment for any offense defined in this chapter and  committed  after
  the  effective  date hereof, as well as the construction and application
  of any defense to a prosecution for such an offense.
    2.  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  of  this
  chapter  and  committed after the effective date thereof, as well as the
  construction and application of any defense to a prosecution for such an
  offense.
    3. The provisions of this chapter  do  not  apply  to  or  govern  the
  construction  of  and  punishment for any offense committed prior to the
  effective date of this chapter, or the construction and  application  of
  any  defense  to a prosecution for 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 chapter
  had not been enacted.