overload-js

overload-js

Function overloading in JavaScript for 3.9KB minified, 1.4KB gzipped.

Provides tools to mimic function overloading that is present in most strictly-types languages. Prevents messy, long, if-statement, type-checking functions that are hard to read and maintain. Style and API inspired by Moreiki and Mongoose.

npm install overload-js

Basic Usage

var hello = (function() {

	var secret = '!';

	return overload()
		.args().use(function() {
			return secret;
		})
		.args(String).use(function(val) {
			secret = val;
		});

}());

hello('world'); // calls setter
hello(); // returns 'world'
hello(0); // throws a Type Error

Detectable types

null
undefined
Infinity
Date
NaN
Number
String
Object
Array
RegExp
Boolean
Function
Element // browser only

Overload with a map

A map can be defined as an overload as well:

var hello = overload.map({
		what: String
	}).use(function(obj) {
		return 'hello ' + obj.what;
	});

hello({ what: 'world!' }); // returns 'hello world!'
hello('world'); // throws a Type Error

or a map can be used as a custom type (see below):

var hello = overload.args(String, o.map({
		what: String
	})).use(function(str, obj) {
		return str + obj.what;
	});

hello('hello', { what: 'world!' }); // returns 'hello world!'
hello('hello', 'world'); // throws a Type Error

Custom types

A custom type can be defined by passing a string and validation function to defineType. The validation function will be passed the value to validate and expects a boolean return.

overload.defineType('
Custom types are available under o.
var overload = require('overload-js'),
	o = overload.o;
var method = overload().args(o.$).use(function($elem) {
	console.log($elem);
});

method(); // fails
method(''); // fails
method($('body')); // succeeds
Additional types
o.any() accepts multiple types that a parameter will match against.
var method = overload().args(o.any(String, Number)).use(function() {
	console.log('passed!');
});

method(); // fails
method([]); // fails
method(''); // passed!
method(0); // passed!
The inverse of o.any is o.except.
var method = overload().args(o.except(Object)).use(function() {
	console.log('passed!');
});

method(); // passed!
method([]); // passed!
method({}); // fails
Also available are o.truthy and o.falsy.
var method = overload()
	.args(o.truthy).use(function() {
		console.log('truthy');
	})
	.args(o.falsy).use(function() {
		console.log('falsy');
	});

method(); // fails
method(0); // falsy
method(1); // truthy
Overloading by length
In addition to overloading by type, argument length can be used.
If a number is not passed, the function.length will be used.
var method = overload()
		.len(0).use(function() {
			console.log('0 args');
		})
		.len(1).use(function(a) {
			console.log('1 arg');
		})
		.len().use(function(a, b, c) {
			console.log('3 args');
		});

method(); // '0 args'
method({}); // '1 arg'
method(null, [], {}); // '3 args'
alias: count, size
If args and length are used in the overload, args will be matched
first, followed by length.
Fallback
A fallback function can be defined via the fallback method.
var method = overload().args(String).use(function(a) {
				console.log(a);
			})
			.fallback(function() {
				console.log('handled!');
			});
method('hello'); // 'hello'
method(); // 'handled'
If a fallback is not defined and the exposed method is called
without a matching function, an error will be thrown...
Expose
A clean function can be exposed so that overload properties
and methods are hidden from the outside world. 
var method = overload()
	.args().use(function() {
		return 'hi';
	})
	.expose();

// method.args === undefined
// method.use === undefined
// etc...
Errors
The error from unmatched calls can be handled by defining your own err method on overload or
by passing a function to handle the error.
overload.err = function() {
	console.log('there was an error');
};

overload()
	.error(function() { console.trace(); })
Support

Node.js, modern browsers and IE8+
To run the tests, simply open test/index.html in your favorite browser or run npm test.
#License
The MIT License (MIT)
Copyright (c) 2014 Joseph Clay
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
, function(val) {
	return val instanceof jQuery;
});

Custom types are available under __INLINE_CODE_5__.

__CODE_BLOCK_5__

Additional types

__INLINE_CODE_6__ accepts multiple types that a parameter will match against.

__CODE_BLOCK_6__

The inverse of __INLINE_CODE_7__ is __INLINE_CODE_8__.

__CODE_BLOCK_7__

Also available are __INLINE_CODE_9__ and __INLINE_CODE_10__.

__CODE_BLOCK_8__

Overloading by length

In addition to overloading by type, argument length can be used. If a number is not passed, the __INLINE_CODE_11__ will be used.

__CODE_BLOCK_9__

alias: __INLINE_CODE_12__, __INLINE_CODE_13__

If __INLINE_CODE_14__ and __INLINE_CODE_15__ are used in the overload, args will be matched first, followed by length.

Fallback

A fallback function can be defined via the __INLINE_CODE_16__ method.

__CODE_BLOCK_10__

If a fallback is not defined and the exposed method is called without a matching function, an error will be thrown...

Expose

A clean function can be exposed so that overload properties and methods are hidden from the outside world.

__CODE_BLOCK_11__

Errors

The error from unmatched calls can be handled by defining your own __INLINE_CODE_17__ method on __INLINE_CODE_18__ or by passing a function to handle the error.

__CODE_BLOCK_12__

Support

Node.js, modern browsers and IE8+

To run the tests, simply open test/index.html in your favorite browser or run __INLINE_CODE_19__.

#License

The MIT License (MIT)

Copyright (c) 2014 Joseph Clay

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.