node-procedural-async

Write procedural style code that runs asynchronously. It may look synchronous, but it's not!

Basic Example

var Bernhard = require('procedural-async');
var models = require('./models');
 
Bernhard.async(function(){
    try {
        // Not needed now, don't block.
        var current_user = models.User.retrieveByName(req.session.username);
        var genre = models.Genre.retrieveByName(req.query.genre);
        // Will wait on results.
        var book_results = models.Book.search({genre: genre.id});
        var favorite_book_ids = current_user.retrieveFavoriteBookIds();
        var response_data = book_results.map(function(book){
            return {
                id: book.id,
                title: book.title,
                author: book.retrieveAuthor().name,
                is_favorite: favorite_book_ids.indexOf(book.id) > -1
            };
        });
    } catch (e) {
        return next(e);
    }
    
    res.json(response_data);
});

Full Example Code

Features

• Fully asynchronous, with the option to be synchronous
• Execute asynchronous calls immediately, but wait for the results only at the time you need them
• Allows for try/catch error handling
• instances are subclasses of any class you like
• Easy to read and write

How it Works

Under the hood, node-procedural-async uses a combination of Proxies and node-fibers. When you call Bernhard.generate, a proxy class is dynamically generated, instanciated and returned. All calls to the proxy will yield until whatever asynchronous task you started has completed. The asynchronous/synchronous magic comes from fibers, so you must write your procedural-async code inside a function that you pass to Bernhard.async.

Installation

The current version requires node.js v0.11.4 and an experimental untagged version of node-fibers.

• Install nvm: curl https://raw.github.com/creationix/nvm/master/install.sh | sh
• Install node: nvm install 0.11.4
• Install dependencies: npm install procedural-async
• Run with harmony: node --harmony your_file.js

Usage

Setting Up Your Asynchronous Code

Bernhard.generate(Class)

Returns an instance that derives from Class. You should return this instance from your asynchronous function immediately.

instance.callback([err, [result]])

Call this on the instance you got from Bernhard.generate when your asynchronous function has completed.

Using Your Asynchronous Code

Bernhard.async(function)

Put all your procedural-async code inside a function that you pass to this method. Inside this function, you can try/catch any errors.

Authors

This library was developed by Ben Kovacevich, David Fenster, and Carlos Gomez at Shutterstock

License

Copyright (C) 2013 by Shutterstock Images, LLC

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.