use string enums and symbols as index types

enum_demo.ts

enum Stats {
	int = 'int does stuff',
	str = 'str does other stuff',
	def = 'def prevents stuff',
}

type StatName = keyof typeof Stats

interface HasStats {
	stats: {
		[key in StatName]: number
	}
}

class Thing implements HasStats {
	stats = {
		int: 20,
		str: 20,
		def: 20
	}
}

symbol_demo.ts

const int = Symbol('int')
const str = Symbol('str')
const def = Symbol('def')

type StatName = typeof int | typeof str | typeof def

interface HasStats {
	stats: {
		[key in StatName]: number
	}
}

class Thing implements HasStats {
	stats = {
		[int]: 20,
		[str]: 20,
		[def]: 20
	}
}