Direct port of python's Twisted Deferred module to coffeescript and thus javascript.

Links:

• Twisted Docs

Installation

git clone git://github.com/my8bird/nodejs-twisted-deferreds.git 
cd nodejs-twisted-deferreds
(sudo) npm link

Dependencies:

• coffeescript
• nodeunit (for running the tests)

Usage

This is a contrived example that reads the contents of a file, trims the whitespace and prints the result to the console. If an error occurs then it is logged.

fs    = require('fs')
defer = require('twisted-deferred')
Deferred = defer.Deferred

# Create Deferred instance that will track the steps
d = new Deferred()

# Add a step that cleans the content
d.addCallback (content) ->
    return content.trim()

# Add a step that uses the cleaned content
d.addCallback (cleanedContent) ->
    console.log cleanedContent

# If there is an error at any step make sure it is logged.
d.addErrback (err) ->
    console.error err

# Grab the content from the file and start the procedure
fs.readFile "path", "r", (err, data) ->
    if err
        d.errback err
    else
        d.callback data

It is also possible to wrap existing async code using the toDeferred method: d = defer.toDeferred(fs.readFile, "path") d.addCallback (content) -> console.log content d.addErrback (err) -> # log err

Tests

To run the tests ensure that nodeunit is installed. Then run run-tests.sh.