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_trait::enum_names

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

enum_trait::enum_length

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

11.13.2. Handled enumerations

enum_trait::string_to_enum

Enumeration annotation which implements string constructor for enumeration.

11.13.3. Enumeration iteration

• each (tt: auto(TT)) : iterator<TT>

enum_trait::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>

• string (arg: auto) : auto

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

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

enum_trait::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)

enum_trait::string(arg: auto) : auto()

converts enum value to string

usage: let s = string(EnumValue)

Arguments

• arg : auto

11.13.4.1. to_enum

enum_trait::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

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