Macros 2.0

#39412

Note

Macros 2.0 is a proposal to improve the macros 1.0 (declarative macros macro_rules!). It is not yet implemented.

Why Macros 2.0?

Macros 1.0 has several limitations:

• Lack of hygiene: Macros 1.0 can capture variables from the surrounding scope, which can lead to unexpected behavior.
• Lack of modularity: Macros 1.0 cannot be easily composed or reused.
• Lack of type safety: Macros 1.0 cannot be easily checked for type safety.

Macros 2.0 aims to address these limitations by providing a more powerful and flexible macro system.

Note

We will get it back when it is implemented.

Tip

We actually don’t need macros 1.0 or macros 2.0, if we can use procedural macros.