For now, this reference is a best-effort document. We strive for validity and completeness, but are not yet there. In the future, the docs and lang teams will work together to figure out how best to do this. Until then, this is a best-effort attempt. If you find something wrong or missing, file an issue or send in a pull request.

Enumeration Variant expressions

Syntax
EnumerationVariantExpression :
      EnumExprStruct
   | EnumExprTuple
   | EnumExprFieldless

EnumExprStruct :
   PathInExpression { EnumExprFields? }

EnumExprFields :
      EnumExprField (, EnumExprField)\* ,?

EnumExprField :
      IDENTIFIER
   | (IDENTIFIER | TUPLE_INDEX) : Expression

EnumExprTuple :
   PathInExpression (
      ( Expression (, Expression)\* ,? )?
   )

EnumExprFieldless : PathInExpression

Enumeration variants can be constructed similarly to structs, using a path to an enum variant instead of to a struct:


# #![allow(unused_variables)]
#fn main() {
# enum Message {
#     Quit,
#     WriteString(String),
#     Move { x: i32, y: i32 },
# }
let q = Message::Quit;
let w = Message::WriteString("Some string".to_string());
let m = Message::Move { x: 50, y: 200 };
#}

Enum variant expressions have the same syntax, behavior, and restrictions as struct expressions, except they do not support base update with the .. syntax.