2.5. Enums#

Syntax#

EnumDefinition = (* enum_keyword: *) ENUM_KEYWORD
                 (* name: *) IDENTIFIER
                 (* open_brace: *) OPEN_BRACE
                 (* members: *) EnumMembers
                 (* close_brace: *) CLOSE_BRACE;

EnumMembers = ((* item: *) IDENTIFIER ((* separator: *) COMMA (* item: *) IDENTIFIER)*)?;

Enum Types#

Enums can be used to create custom types with a finite set of constant values. Enums can be declared on the file level, outside of contract or library definitions.

enum ActionChoices {
    One,
    Two
}

contract MyContract {
    function choose() public pure returns (ActionChoices) {
        return ActionChoices.Two;
    }
}

Enums require at least one member, and its default value when declared is the first member. Enums cannot have more than 256 members.