Node Roundup: 0.11.2, 0.10.6, subscribe, Omelette

15 May 2013 | By Alex Young | Tags node modules cli events pubsub
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Node 0.11.2 and 0.10.6

Clearly the Node core developers have had an early summer holiday, and are now back to unleash new releases. In the space of a few days 0.11.2 and 0.10.6 were released. I was intrigued by the Readable.prototype.wrap update, which makes it support objectMode for streams that emit objects rather than strings or other data.

The 0.11.2 release has an update that guarantees the order of 'finish' events, and another that adds some new methods: cork and uncork. Corking basically forces buffering of all writes – data will be flushed when uncork is called or when end is called.

There is a detailed discussion about cork and the related _writev method on the Node Google Group: Streams writev API. There are some interesting comments about a similar earlier implementation by Ryan Dahl, the validity of which Isaac questions due to Node’s code changing significantly since then.

If you want to read about writev, check out the write(2) (man 2 write) manual page:

Write() attempts to write nbyte of data to the object referenced by the descriptor fildes from the buffer pointed to by buf. Writev() performs the same action, but gathers the output data from the iovcnt buffers specified by the members of the iov array…

subscribe

Azer Koçulu has been working on a suite of modules for subscribing and observing to changes on objects:

Now he’s also released a module for subscribing to multiple pub/sub objects:

var subscribe = require('subscribe');
var a = pubsub();
var b = pubsub();
var c = pubsub();

subscribe(a, b, c, function(updates) {
  updates[0].pubsub;
  // => a.onUpdate
  updates[0].params;
  // => 3, 4
  updates[1].pubsub;
  // => c.onUpdate
  updates[1].params;
  // => 5, 6
});

a.publish(3, 4);
c.publish(5, 6);

This brings a compositional style of working to Azer’s other modules, allowing subscriptions to multiple lists and objects at the same time. The next example uses subscribe to combine the new-list module with new-object:

var fruits = newList('apple', 'banana', 'grapes');
var people = newObject({ smith: 21, joe: 23 });

subscribe(fruits, people, function(updates) {
  updates[0].params[0].add;
  // => melon

  updates[1].params[1].set;
  // => { alex: 25 }
});

fruits.push('melon');
people('alex', '25');

Omelette

Omelette (GitHub: f / omelette, License: MIT, npm: omelette) by Fatih Kadir Akın is a template-based autocompletion module.

Programs and their arguments are defined using an event-based completion API, and then they can generate the zsh or Bash completion rules. There’s an animated gif in the readme that illustrates how it works in practice.


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