Do not define unset boolean args

index.js

@@ -1,7 +1,7 @@
 'use strict';
 const path = require('path');
 const buildMinimistOptions = require('minimist-options');
-const minimist = require('minimist');
+const yargs = require('yargs-parser');
 const camelcaseKeys = require('camelcase-keys');
 const decamelizeKeys = require('decamelize-keys');
 const trimNewlines = require('trim-newlines');
@@ -32,12 +32,24 @@ module.exports = (helpMessage, opts) => {
 		input: 'string',
 		help: helpMessage,
 		autoHelp: true,
-		autoVersion: true
+		autoVersion: true,
+		booleanDefault: false
 	}, opts);
 
+	const minimistFlags = opts.flags && typeof opts.booleanDefault !== 'undefined' ? Object.keys(opts.flags).reduce(
+		(flags, flag) => {
+			if (flags[flag].type === 'boolean' && !Object.prototype.hasOwnProperty.call(flags[flag], 'default')) {
+				flags[flag].default = opts.booleanDefault;
+			}
+
+			return flags;
+		},
+		opts.flags
+	) : opts.flags;
+
 	let minimistOpts = Object.assign({
 		arguments: opts.input
-	}, opts.flags);
+	}, minimistFlags);
 
 	minimistOpts = decamelizeKeys(minimistOpts, '-', {exclude: ['stopEarly', '--']});
 
@@ -47,8 +59,12 @@ module.exports = (helpMessage, opts) => {
 
 	minimistOpts = buildMinimistOptions(minimistOpts);
 
+	if (minimistOpts['--']) {
+		minimistOpts.configuration = Object.assign({}, minimistOpts.configuration, {'populate--': true});
+	}
+
 	const pkg = opts.pkg;
-	const argv = minimist(opts.argv, minimistOpts);
+	const argv = yargs(opts.argv, minimistOpts);
 	let help = redent(trimNewlines((opts.help || '').replace(/\t+\n*$/, '')), 2);
 
 	normalizePackageData(pkg);

package.json

@@ -41,12 +41,12 @@
 		"camelcase-keys": "^4.0.0",
 		"decamelize-keys": "^1.0.0",
 		"loud-rejection": "^1.0.0",
-		"minimist": "^1.1.3",
 		"minimist-options": "^3.0.1",
 		"normalize-package-data": "^2.3.4",
 		"read-pkg-up": "^3.0.0",
 		"redent": "^2.0.0",
-		"trim-newlines": "^2.0.0"
+		"trim-newlines": "^2.0.0",
+		"yargs-parser": "^10.0.0"
 	},
 	"devDependencies": {
 		"ava": "*",

readme.md

@@ -173,6 +173,55 @@ Infer the argument type.
 
 By default, the argument `5` in `$ foo 5` becomes a string. Enabling this would infer it as a number.
 
+##### booleanDefault
+
+Type: `boolean` `null` `undefined`<br>
+Default: `false`
+
+Value of `boolean` flags not defined in `argv`.
+If set to `undefined` the flags not defined in `argv` will be excluded from the result.
+The `default` value set in `boolean` flags take precedence over `booleanDefault`.
+
+Example:
+
+```js
+const cli = meow(`
+	Usage
+	  $ foo
+
+	Options
+	  --rainbow, -r  Include a rainbow
+	  --unicorn, -r  Include a unicorn
+
+	Examples
+	  $ foo
+	  🌈 unicorns 🌈
+`, {
+	booleanDefault: undefined,
+	flags: {
+		rainbow: {
+			type: 'boolean',
+			default: true
+			alias: 'r'
+		},
+		unicorn: {
+			type: 'boolean',
+			default: false
+			alias: 'u'
+		},
+		cake: {
+			type: 'boolean',
+			alias: 'c'
+		}
+	}
+});
+/*
+{
+	flags: {rainbow: true, unicorn: false},
+	…
+}
+*/
+```
 
 ## Promises
 

test.js

@@ -106,8 +106,52 @@ test('type inference', t => {
 	}).input[0], 5);
 });
 
+test('booleanDefault: undefined, filter out unset boolean args', t => {
+	t.deepEqual(m('help', {
+		argv: ['--foo'],
+		booleanDefault: undefined,
+		flags: {
+			foo: {
+				type: 'boolean'
+			},
+			bar: {
+				type: 'boolean'
+			},
+			baz: {
+				type: 'boolean',
+				default: false
+			}
+		}
+	}).flags, {
+		foo: true,
+		baz: false
+	});
+});
+
+test('boolean args are false by default', t => {
+	t.deepEqual(m('help', {
+		argv: ['--foo'],
+		flags: {
+			foo: {
+				type: 'boolean'
+			},
+			bar: {
+				type: 'boolean',
+				default: true
+			},
+			baz: {
+				type: 'boolean'
+			}
+		}
+	}).flags, {
+		foo: true,
+		bar: true,
+		baz: false
+	});
+});
+
 test('enforces boolean flag type', t => {
-	const cli = m(``, {
+	const cli = m('', {
 		argv: ['--cursor=false'],
 		flags: {
 			cursor: {type: 'boolean'}