The Interpretation Act 1957 explains when laws commence and what happens when a law is repealed.

Commencement of laws

If a day is not set for the coming into operation of a law, that day will be the day when the law was first published in the Gazette as a law.

If any act provides

The Interpretation Act 1957 applies to the interpretation of all laws, so it is a useful act to know.

The act was last amended to incorporate the 1993 Interim Constitution. While there are some archaic and strange provisions, like the mention of the former colonies and the Royal Letters Patent of His Majesty King William