Consider API for next major version of Step

[creationix]

https://gist.github.com/1524578#comments

[creationix]

See some background at #7

[creationix]

Also merged with #6

[digitalrinaldo]

Does Step work with events. Suppose you have an imap server that sends multiple message events and an end event after the last message has been sent. How do I get the end event to further wait for the message events to be processed use group?

[creationix]

@digitalrinaldo, Step is meant to be a control-flow structure for async callbacks. Events are a little more complicated, but interface via callbacks.

Group is for cases where you have a finite number of async functions and want to be notified when they are all done. Events on a stream is different because you don't know how many there will be till then "end" event fires.

// Using the old API
Step(
  function () {
    var chunks = [];
    this.parallel(null, chunks);
    var slot = this.parallel();
    emitter.on('data', function (chunk) { chunks.push(chunk); });
    emitter.on('error', slot);
    emitter.on('end', slot); // Assuming end doesn't have any arguments
  },
  function (err, chunks, dummy) {

  }
);

// Using the twostep API
Step(
  function () {
    var chunks = [];
    this.pass(chunks);
    var slot = this.slot();
    emitter.on('data', function (chunk) { chunks.push(chunk); });
    emitter.on('error', slot);
    emitter.on('end', slot); // Assuming end doesn't have any arguments
  },
  function (err, chunks, dummy) {

  }
);

[xavi-]

@creationix, That's a good workaround. I've been manually executing callbacks:

Step(
  function () {
    var chunks = [], next = this;
    emitter.on('data', function (chunk) { chunks.push(chunk); });
    emitter.on('error', function(err) { next(err); });
    emitter.on('end', function() { next(null, chunks) });
  },
  function (err, chunks) {

  }
);

It'd be cool if Step2 had connivence method to better support stream APIs. Maybe something like this:

Step(
  function () {
    this.listen(emitter); // Listens for the data, error, end events for me
    emitter.pipe(this.pipe()) // Or, `this.pipe()` creates a writeable stream
  },
  function (err, chunks1, chunks2) {
    // chunks1 and 2 are arrays of buffers or strings
  }
);

Not sure if you need both this.listen and this.pipe, but having either would definitely get rid of boiler plate. Stream APIs are becoming very popular.