funcify.js: Super funky function overloading
Funcify is a straight forward, easy to use function overloading library written in JavaScript that works in browsers and JS backends.
It allows you to easily create overloaded functions that perform different actions based on the number and types of arguments.
Installing
To install funcify, either:
Install via NPM
npm install funcify
Install via Bower
bower install funcify
Download a release
https://github.com/garydouble/funcify/releases
Getting started
Each overload is defined as an Array of parameter types (filters) and a callback.
The general signature looks like this
funcify(function|array, ...): function
The funcify function returns a new function that handles the overloading.
Here are some examples:
// fn will be an overloaded function.
var fn = funcify(
// fn()
function() {
// This is a "catch-all" function and
// will be called if no specific override exists.
},
// fn(string)
['string', function(someString) {
doSomethingWith(someString);
}],
// fn(*, int)
['any', 'int', function(o, i) { /* ... */ }]
);
Built-in type checking filters
Wildcard / Any type filter
'*'
or 'any'
Allows anything and everything, except undefined
.
String filter
's'
or 'string'
or /regexp/
Validates the parameter is a String
.
var fn = funcify(['string', function(str) { /* ... */ }]);
// yea
fn('hello');
// nay
fn(123);
When a /regexp/
is provided an additional check will be made to ensure the parameter tests positive against the pattern.
var fn = funcify([/^[abc]$/, function(str) { /* ... */ }]);
// yea
fn('a');
fn('b');
fn('c');
// nay
fn('xyz');
fn('abc');
Function filter
'f'
or 'function'
Validates the parameter is a Function
.
var fn = funcify(['function', function(func) { /* ... */ }]);
// yea
fn(function() {});
fn(myPreDefinedFunction);
// nay
fn('hello');
Object filter
'o'
or 'object'
Validates the parameter is an Object
literal, explicitly.
var fn = funcify(['object', function(obj) { /* ... */ }]);
// yea
fn({});
// nay
fn('hello');
fn([]);
fn(new Date());
Array filter
'a'
or 'array'
Validates the parameter is an Array
or "Array-like".
var fn = funcify(['array', function(arr) { /* ... */ }]);
// yea
fn([1, 2, 3]);
fn(new Float32Array())
fn(arguments)
// nay
fn('hello');
fn({});
RegExp filter
'r'
or 'regexp'
Validates the parameter is a RegExp
.
Not to be confused with pattern matching, for that see the String
filter.
var fn = funcify(['regexp', function(rx) { /* ... */ }]);
// yea
fn(/abc/);
fn(new RegExp());
// nay
fn('hello');
fn({});
Boolean filter
'b'
or 'boolean'
Validates the parameter is either true
or false
.
var fn = funcify(['boolean', function(b) { /* ... */ }]);
// yea
fn(true);
fn(false);
// nay
fn([]);
fn('true');
fn(0);
Date filter
'd'
or 'date'
Validates the parameter is a Date
.
var fn = funcify(['date', function(date) { /* ... */ }]);
// yea
fn(new Date());
// nay (sorry not yet)
fn(moment()); //
fn('2017-12-17');
fn(5873242342);
Number filter
'n'
or 'number'
Validates the parameter is a Number
.
var fn = funcify(['number', function(n) { /* ... */ }]);
// yea
fn(123);
fn(4.56);
fn(NaN);
fn(Infinity);
Int filter
'int'
Validates the parameter does not equal NaN
when passed through parseInt
.
var fn = funcify(['int', function(i) { /* ... */ }]);
// yea
fn(123);
fn(4.56);
// nay
fn(NaN);
fn(Infinity);
Float filter
'float'
Validates the parameter does not equal NaN
when passed through parseFloat
.
var fn = funcify(['float', function(f) { /* ... */ }]);
// yea
fn(123);
fn(4.56);
// nay
fn(NaN);
fn(Infinity);
Class filter
Class
Validates the parameter is an instance of a particular class.
var fn = funcify([MyClass, function(inst) { /* ... */ }]);
var inst = new MyClass();
// yea
fn(inst);
Defining your own filters
Filters are defined as factory functions that return new functions that act upon a single argument parameter and return true or false depending on whether said parameter meets the specific filter requirements.
To define a custom filter simply attach a factory function to a property on the funcify.filters
object.
// Register your shiney new filter.
funcify.filters['binary'] = function() {
return function(arg) {
return /^[01 ]+$/.test(arg);
};
};
// Configure an overload that uses it
var fn = funcify(['binary', function(bitString) {
return convertToAscii(bitString); // or whatever!
}]);
Once a new filter has been defined you can then refer to it in your signature specifications.
// Call your function with the new override
var howCoolIsThis = fn('01000101 01010000 01001001 01000011');
Issues and Contributions
https://github.com/garydouble/funcify/issues
Issues, feedback and pull requests all welcome.
Happy Coding!