Coffeescript class and Handlebars template and custom block helper

Question

When I use Handlebars.compile on a variable it works well, but when I put the function on a Coffee class property, it give me undefined , bug? Or I miss some basic java/coffee functionality?

There is my fiddle: http://jsfiddle.net/Cl0udW4lk3r/BpY5b/

class Test
  template: Handlebars.compile (
    """
    {{#iterate data}}
        <p>{{data}}</p>
    {{/iterate}}
    """
  )

template = Handlebars.compile (
  """
  {{#iterate data}}
    <p>{{data}}</p>
  {{/iterate}}
  """
)

There is another fiddle with backbone in action: http://jsfiddle.net/Cl0udW4lk3r/D3FR9/20/

---- UPDATE -----

My first fiddle is solved (but the handlebars version was outdated), and the error was a stupid OOP inattention...

But! My second fiddle (and now that I've updated the first fiddle's handlebars resource, also my first fiddle..) give to me an error

TypeError: callback is not a function

It seems that the callback part is not right processed... the error is the same both on coffee class or simple variable case...

Answer 1

When you say this:

class Test
  template: ...

you're defining template as an instance property so you'd have to create an instance before you could look at template :

t = new Test
console.log(t.template)

Or you could dig the template out of Test 's prototype:

console.log(Test::template)

If you want template to be a class property then:

class Test
  @template: ...

Demo: http://jsfiddle.net/ambiguous/tvDpN/

---

Your second issue is related to a change in how Handlebars helpers get called. The last argument used to be the callback function and you'd use fn.inverse for the {{else}} block. The last argument to the helper is now an object with the function in .fn and the else-block function in .inverse . So for the latest versions of Handlebars, your helper:

Handlebars.registerHelper 'iterate', (context, callback) ->
    switch typeof context
        when 'object' then (callback(key: key, value: value) for own key, value of context).join ''

should looks more like this:

Handlebars.registerHelper 'iterate', (context, options) ->
    switch typeof context
        when 'object' then (options.fn(key: key, value: value) for own key, value of context).join ''

Demo: http://jsfiddle.net/ambiguous/NQZTG/

Answer 2

It's because you're inspecting the template property of the Test class itself, instead of instantiating a new instance of the Test class and inspecting the property on that instance. The following should work:

$ ->
  console.log new Test().template
  console.log template