Structs

Syntax
Struct :
      StructStruct
   | TupleStruct

StructStruct :
   struct IDENTIFIER  Generics? WhereClause? ( { StructFields? } | ; )

TupleStruct :
   struct IDENTIFIER  Generics? ( TupleFields? ) WhereClause? ;

StructFields :
   StructField (, StructField)* ,?

StructField :
   OuterAttribute*
   Visibility?
   IDENTIFIER : Type

TupleFields :
   TupleField (, TupleField)* ,?

TupleField :
   OuterAttribute*
   Visibility?
   Type

A struct is a nominal struct type defined with the keyword struct.

An example of a struct item and its use:


#![allow(unused_variables)]
fn main() {
struct Point {x: i32, y: i32}
let p = Point {x: 10, y: 11};
let px: i32 = p.x;
}

A tuple struct is a nominal tuple type, also defined with the keyword struct. For example:


#![allow(unused_variables)]
fn main() {
struct Point(i32, i32);
let p = Point(10, 11);
let px: i32 = match p { Point(x, _) => x };
}

A unit-like struct is a struct without any fields, defined by leaving off the list of fields entirely. Such a struct implicitly defines a constant of its type with the same name. For example:


#![allow(unused_variables)]
fn main() {
struct Cookie;
let c = [Cookie, Cookie {}, Cookie, Cookie {}];
}

is equivalent to


#![allow(unused_variables)]
fn main() {
struct Cookie {}
const Cookie: Cookie = Cookie {};
let c = [Cookie, Cookie {}, Cookie, Cookie {}];
}

The precise memory layout of a struct is not specified. One can specify a particular layout using the repr attribute.