effective-enum
for the time being, the typescript enum type is quite hard to use, this repo tries to implement a typesafe enum pattern described in the first edition of effective java
installation
via npm
npm install effective-enum --save
via yarn
yarn add effective-enum
getting started
import {EnumClass, EnumValue, EnumFactory} from 'effective-enum';
@EnumClass
class Color extends EnumFactory<Color>() {
@EnumValue
static readonly RED = new Color('红');
@EnumValue
static readonly BLUE = new Color('蓝');
constructor(
public label: string,
) {
super();
}
}that's it, both Color and its instances are immutable, which means you can not add,remove or change a color after definition.
Color.values() // => [Color.RED, Color.BLUE]
Color.of('RED') // => Color.RED
Color.RED.toString() // => "RED"
Color.RED.name // => "RED"
JSON.stringify(Color.RED) // => "RED"
Color.RED.label // => "红"
Color.RED instanceof Color // true
Color.BLACK = 'whatever' // error
Color.RED.label = 'whatever' // error
new Color() // error
Color() // errordrawback compare to typescript built in enum
In interface definition block, you can only use string/number/unique symbol as property keys. for example:
import {EnumClass, EnumFactory} from './index';
enum BuiltInColorEnum {
RED = 'RED',
BLUE = 'BLUE'
}
@EnumClass
class EffectiveColorEnum extends EnumFactory<EffectiveColorEnum>() {
@EnumValue
static readonly RED = new Color();
@EnumValue
static readonly BLUE = new Color();
}
interface SomeInterface {
[BuiltInColorEnum.RED]: string; // this should work
[EffectiveColorEnum.RED]: string; // compile time error
}Anyway, one can make use of Merging Namespaces with Classes approach. to combine these two types of enum definition. e.g.
import {EnumClass, EnumValue, EnumFactory} from 'effective-enum';
namespace Color {
export enum Constant {
RED = 'RED',
BLUE = 'BLUE',
}
}
@EnumClass
export class Color extends EnumFactory<Color>() {
@EnumValue
static readonly RED = new Color();
@EnumValue
static readonly BLUE = new Color();
}
interface SomeInterface {
[Color.Constant.RED]: string;
[Color.Constant.BLUE]: string;
}
Color.RED.name // => "RED"license
MIT