remcoder / computron

Computron is for creating reactive computations, just like ReactiveVar is for reactive values

Computron

Computron is for creating reactive computations, just like ReactiveVar is for reactive values and was inspired by computed values from Knockout and Vue.js.

Example

var r1 = new ReactiveVar(21);
var r2 = new ReactiveVar(21);

var sum = new Computron(function () {
  return r1.get() + r2.get();
});

Installation

$ meteor add remcoder:computron

Rationale

While Meteor offers a very flexible way of doing reactivity, having to wrap code in an autorun doesn't always lead to code that makes the intent clear. This becomes most apparent when you have a cascade of reactive vars that each depend on one of the other, mixed with side-effects.

TODO: some good examples

Demo

See in in action here

API

Creation

var comp = new Computron(<computation>)

computation : a function that returns a value. It can make use of reactive sources like Session, ReactiveVar etc.

Example

var taxRate = 0.2;
var priceAfterTax = new Computron(function(){
	return Session.get('price') * (1 + taxRate);
});

To get the current value of the computation, call the get() method it. For instance:

 Session.set('priceLabel', 'total :' + priceAfterTax.get() )

The computed value will be updated reactively and propagated to the dependents of the Computron.

Advanced

The underlying Tracker.Computation is accessible from within the callback. Using that you could for instance stop() the computation.

var priceAfterTax = new Computron(function(comp) {
	if (sometging) 
		comp.stop();
	return Session.get('price') * (1 + taxRate);
});