A simple way to overload a function depending on the type of the parameters passed to it.

Create a mathod taking different types and number of arguments by calling overload. The returned method can be called just like any other function.

var createPerson = overload([String], function(name){
	return "name: "+name;
}).when([String, Number], function(name, age){
	return createPerson(name)+", age: "+age;
}).when([String, Number, Function], function(name, age, callback){
	return callback(name, age);
});



createPerson("JavaScript") //returns 'name: JavaScript'
createPerson("JavaScript", 18) //returns 'name: JavaScript, age: 18'
createPerson("JavaScript", 18, function(name, age){
	return "age: "+age+", name: "+name;
}) //returns 'age: 18, name: JavaScript'

If nothing matches, a fallback function will be called:

var myMethod = overload([String], function(value){
	return value.toUpperCase();
}).fallback(function(){
	throw Error("what happened here?" + arguments);
});


myMethod() //throws error

You can create your own instances and use the constructor to match

function Person(name, age){
	this.name = name;
	this.age = age;
}

var getAge = overload([Person], function(person){
	return person.age
}).when([Number], function(age){
	return age;
});


getAge(new Person("JavaScript", 18)) //returns 18
getAge(18) //returns 18

Copyright ©2013 Marius Gundersen All Rights Reserved.

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