design.md

Learning objectives

• Know what explicit and implicit casts are.
• Know how to do an explicit cast.
• Know how to use is and as to cast types.
• Know how to use the typeof operator.
• Pattern matching on types.

Out of scope

• Custom explicit and implicit cast operators.
• Memory and performance characteristics.

Concepts

• casting: know what explicit and implicit casts are; know how to do an explicit cast; know how to use is and as to convert between types.
• implicit-casting: know about implicit type conversion

Prerequisites

• numbers: know how to cast numbers and what explicit and implicit numeric casts are.
• inheritance: work with inheritance to show when casting can be reasonably used.
• exceptions: know about exceptions to understand what happens when an explicit cast fails.