Enum @VERSION@ - Simulate Enums in Lua
This is a little module that simulates enumerated types in Lua.
Its API is very similar to the Python3 Enum API, although much more limited.
Example Usage
enum = require("enum")
sizes = {"SMALL", "MEDIUM", "BIG"}
Size = enum.new("Size", sizes)
print(Size) -- "<enum 'Size'>"
print(Size.SMALL) -- "<Size.SMALL: 1>"
print(Size.SMALL.name) -- "SMALL"
print(Size.SMALL.value) -- 1
assert(Size.SMALL ~= Size.BIG) -- true
assert(Size.SMALL < Size.BIG) -- error "Unsupported operation"
assert(Size[1] == Size.SMALL) -- true
Size[5] -- error "Invalid enum member: 5"
-- Enums cannot be modified
Size.MINI -- error "Invalid enum: MINI"
assert(Size.BIG.something == nil) -- true
Size.MEDIUM.other = 1 -- error "Cannot set fields in enum value"
-- Keys cannot be reused
Color = enum.new("Color", {"RED", "RED"}) -- error "Attempted to reuse key: 'RED'"Installing
Using "classic" nix
If you are on NixOS, you can install this package from nix-stefano-m-overlays.
Using nix flakes
This package can be installed as a nix
flake. It provides packages for the various
versions of Lua shipped with nix as well as an
overlay that adds the enum attribute to
the Lua package sets.
NOTE
To ensure that the flake overlays are composable, enum is added directly to
the top-level luaPackages. An unfortunate consequence is that enum will
not be present in lua.pkgs. To use enum in lua.withPackages, one must
refer to the top-level luaPackages.
For example, say that you want a Lua environment with enum and http, you
need to do something like:
let
# assume that enumOverlay is the overlay provided by the enum flake.
pkgs = import <nixpkgs> {overlays = [enumOverlay];};
in
# http is present in lua.pkgs
# enum is not present in lua.pkgs
myLuaEnv = pkgs.lua.withPackages(ps: [ps.http pkgs.luaPackages.enum])Using Luarocks
This package is published to Luarocks as
enum and can be installed using
luarocks install enum