In this fourth course, we’ll be taking a look at concepts we deal with on a daily basis – weeks, relative dates, durations, time zones – but which are often more complex to code than they appear.

Starting with our stmp class, we’re going to enrich its API with functions capable of handling these concepts in a clear, robust and reusable way.

We’ll see how :

• calculate calendar benchmarks (e.g. Monday of a week),
• display relative dates (“today”, “yesterday”, “next Monday”),
• intelligently format durations into readable segments,
• calculate dates such as “last Sunday in March” or “2nd Sunday in September”.

In addition to the calculations themselves, this course focuses on :

• flexible API design (use of variants),
• anticipated code evolution ( Case of structure designed for tomorrow),
• managing shared properties in a singleton class,
• dynamic indirection (This[$function].apply) to prepare for extensibility.

This course shows that timestamps are not just used to store dates: they become a real temporal abstraction tool at the heart of application logic.