Alias Any Type

C# 12 lifted a long-standing restriction on the using alias directive. Before C# 12, the right side of using Alias = ...; had to be a named type or a namespace. As of C# 12, it can be almost any type the compiler knows about, including tuples, constructed generics, arrays, pointers, and nullable value types. The result is shorter, more readable code in the places where C#'s type names had grown the most uncomfortable: long generic signatures, repeated tuple shapes, and nested array types.

This lesson covers what the new alias form lets you do, the rules and limits the compiler enforces, and the patterns that actually pay off in real e-commerce code.