Env Vars as Booleans

___boolean_env_vars.md

Boolean Environment Variables

Don't overcomplicate things.

I've seen a lot of parse the env var and match it against some known values like:

env_var = ENV['FEATURE_ONE']
case env_var.to_s.downcase
when 'true', 't', 'yes', 'y', 'on', '1' then true
when 'false', 'f', 'no', 'n', 'off', '0' then false
else raise ArgumentError, 'Invalid input detected'
end

This is unecessarily bloated. It also doesn't help that much.
Use the existence of an env var as a guard if something is on or off.

That means: only set env vars if you need them.
Also: if you know a variable is set and you need to turn it off, simply use unset FEATURE_ONE.
Done.

boolenv.js

'use strict';

const isSet = function(envKey) {
  return (envKey in process.env);
}

module.exports = {
  isSet,
  enabled: isSet
}

/*
USAGE:

const { enabled } = require('./boolenv.js');
const featureOneEnabled = enabled('FEATURE_ONE');
console.log('feature one enabled:', featureOneEnabled);
*/

boolenv.rb

module Boolenv
  class << self
    def is_set(env_key)
      ENV.key?(env_key)
    end

    alias enabled is_set
  end
end

__END__

USAGE:
require('./boolenv.rb')
feature_one_enabled = Boolenv.enabled('FEATURE_ONE')
puts "feature one enabled: #{feature_one_enabled}"