Antiquefy

Create callback-last style functions from functions returning promises and from generator functions.

Installation

Install from NPM:

npm install antiquefy

Require Antiquefy in your code:

var antiquefy = require('antiquefy');

Examples

In most cases asynchronous functions which return their results in a callback function can be easily promisified using various promise libraries. However, if you have a 3rd party function which takes a hook-like function with a done callback, the process is not so straightforward.

For example, passport-local strategy takes a verify callback function which is itself supplied with a done callback. Antiquefy handles the calling of the done callback automatically after the antiquefied function has been finished. The done callback is expected to be an error first style callback.

Generators

Here is the antiquefied version of the Passport local strategy example using generators:

passport.use(new LocalStrategy(antiquefy(
    function*(username, password) {
        var user = yield User.findOne({ username: username });
 
        if (!user) {
            return false;
        }
        
        if (!user.verifyPassword(password)) {
            return false;
        }
        
        return user;
    }
)));

Promises

The above could also be achieved using promises:

passport.use(new LocalStrategy(antiquefy(
    function(username, password) {
        return User.findOne({ username: username }).then(function(user) {
 
            if (!user) {
                return false;
            }
        
            if (!user.verifyPassword(password)) {
                return false;
            }
        
            return user;
        });
    }
)));

Functionally this is equivalent to the generator example, but is little more verbose and requires one extra indentation level.

API

antiquefy(fn, [options]) ⇒ Function

Convert the given function or generator function into a function which takes a done callback.

Param	Type	Description
fn	Function or GeneratorFunction	The function (or generator function) to Antiquefy.
options	Object	Options for Antiquefy.
options.spread	boolean	Set this to true if you wish to spread the returned array elements as individual arguments for the done callback. Optional Default: false

Spreading arguments

If the done callback takes more than one parameter, it can be supplied multiple arguments by returning an array and setting the spread option to true.

var sum = antiquefy(function(a, b) {
    return [a, b, a + b];
}, { spread: true });
 
sum(4, 6, function(error, first, second, sum) {
    console.log(first); // 4
    console.log(second); // 6
    console.log(sum); // 10
});

This works similarly to Bluebird's asCallback(..) and that is what Antiquefy uses internally.

Tests

Unit tests can be run by executing:

npm test