Rust的Attribute

参考资料: Attribute

Syntax
InnerAttribute :
   # ! [ Attr ]

OuterAttribute :
   # [ Attr ]

Attr :
   SimplePath AttrInput?

AttrInput :
      DelimTokenTree
   | = Expression

• Inner attributes, written with a bang (!) after the hash (#), apply to the item that the attribute is declared within.
• Outer attributes, written without the bang after the hash, apply to the thing that follows the attribute.

Attributes能够分类为以下几类:

• built-in attributes
• Macro attributes
• Derive macro helper attributes
• Tool attributes

1. Testing Attributes

参考资料: https://doc.rust-lang.org/reference/attributes/testing.html

The test attribute marks a function to be executed as a test.

Derive

Derive作用主要有两点:

1. use the MetaListPaths to specify a list of traits to implement
2. or paths to derive macro to process

简而言之, derive的作用一个是指定trait(可以认为是Java中接口的近亲), 另一个作用是指定derive macro宏.