Duster-Ko

Duster-KO is a Dust.JS[1] implementation & hack-up of a Knockout[2] Template Engine[3]. There's not a lot of the well famed uber-schmancy asynchronous & parallel Dust.js super-powers going on; this is a pretty straight & simple means of using Dust.js templates.

Table of Contents

  usage
  implementation
  why the dust hack
    the source
  references

Usage

Is pretty straightforwards:

• include and give an id for each compiled dust template: <script type="application/javascript" src="mytemplate.dust.js" id="mytemplate"/>
• bind to it. <div data-bind="mytemplate"/>
• ko.applyBindings(myModelView)
• ...
• uh, you also neeed to hack Dust. :( (hack already done & provided)

Implementation

Oh, pretty straightforwards, not much magic.

• Create a Dust helper-filter and make it default, to evaluate Observerable objects properly (call as a function with no arguments).
• Derive a utterly vanilla Knockout Template Engine that calls into Dust.
• A small hack to Dust to keep it from trying to evaluate Observables like functional Dust tags. See: :(

Why the Dust hack

:(

Unpleasant business, that.

Dust expects any functional tags to accept a set of parameters (chunk, context). We could build a Dust-friendly wrapper for every KO Observer, and build Dust contexts out of these, but that seems like an awful lot of unnecessary object creation.

Instead, we just hack Dust to not evaluate Observers like it normally would, and handle the aftermath with a more stock standard helper-filter.

The Source

These changes are done in whatever dust*js you're using.

Prime hackery:

Chunk.prototype.reference = function(elem, context, auto, filters) {
-  if (typeof elem === "function") {
+  if (typeof elem === "function" && elem.name != "observable") {
     elem = elem(this, context, null, {auto: auto, filters: filters});`

Oh, also, we're manually invoking some Dust templates & cough eval'ing that. To manually invoke the template, we need to pass in a Dust Chunk object, which normally we wouldn't be exposed to, so:

+dust.chunk= Chunk

Tis all! Checkout lib/dust-patch.js for a patch against unspecified Dust sources (for now, dust-core-0.3.0.js is the intended target).

References

1. http://akdubya.github.com/dustjs/
2. http://knockoutjs.com/
3. https://github.com/SteveSanderson/knockout/blob/master/src/templating/templateEngine.js