11.13. Enumeration traits

The ENUM_TRAIT module provides reflection utilities for enumerations: iterating over all values, converting between enum values and strings, and building lookup tables. The [string_to_enum] annotation generates a string constructor for the annotated enum type.

All functions and symbols are in “enum_trait” module, use require to get access to it.

require daslib/enum_trait

Example:

require daslib/enum_trait

    enum Color {
        red
        green
        blue
    }

    [export]
    def main() {
        print("{Color.green}\n")
        let c = to_enum(type<Color>, "blue")
        print("{c}\n")
        let bad = to_enum(type<Color>, "purple", Color.red)
        print("fallback = {bad}\n")
    }
    // output:
    // green
    // blue
    // fallback = red

11.13.1. Typeinfo macros

enum_names

Implements typeinfo(enum_names EnumOrEnumType) which returns array of strings with enumValue names.

enum_length

Implements typeinfo(enum_length EnumOrEnumType) which returns total number of elements in enumeration.

11.13.2. Handled enumerations

string_to_enum

Enumeration annotation which implements string constructor for enumeration.

11.13.3. Enumeration iteration

each(tt: auto(TT)): iterator<TT>

Returns an iterator over all values of the given enumeration type.

Arguments:

  • tt : auto(TT)

11.13.4. Enumeration conversion

enum_to_table(ent: auto(EnumT)): table<string, EnumT>
converts enum type to a table of name => value pairs

usage: let t = enum_to_table(type<EnumType>)

Arguments:

  • ent : auto(EnumT)

string(arg: auto): auto
converts enum value to string

usage: let s = string(EnumValue)

Arguments:

  • arg : auto

11.13.4.1. to_enum

to_enum(ent: auto(EnumT); name: string): EnumT
converts string to enum value, panics if not found

usage: let e = to_enum(type<EnumType>,”EnumValueName”)

Arguments:

  • ent : auto(EnumT)

  • name : string

to_enum(ent: auto(EnumT); name: string; defaultValue: EnumT): EnumT