include helper

[c089]

See associated discussion on js implementation:

• Context different for partial handlebars-lang/handlebars.js#182

And the pull request which I tried to port here:

• added 'include' helper for #182 handlebars-lang/handlebars.js#368

I think this is a very helpful feature for people sharing templates between .java and .js as it can be used to replace simple helper functions which otherwise would require two implementations (one in java and one in javascript).

Note that it currently only passes a simpler test than the original pull request, because accessing the parent context seems to require a change to the parser which I did not want to dive into before I know that this has a chance of actually going in. I'd be happy to implement it though if you point me to the right place to make the change :)

I also think that the merge method should be refactored to the Context class itself but wanted the change to be minimally invasive for now so people who need this can easily add it to their own code.

[jknack]

Hi Chris,

If I understand this correctly, the include helper isn't necessary. Here is an explantation.

Partials as the Mustache Spec specify should propagate the caller context.

Also, since #94 is it even possible to switch the context to anything you want:

Examples:

  {{> partial}} same as {{> partial this}}

Or:

  {{> partial context}}

Or:

  {{> partial ../}}

So, unless I'm missing something include helper is just an alias for native partials, right?

Thanks

[c089]

To be honest, I'm not sure about the use case with traversing up in the context, I just ported the test until I saw it didn't parse ;) My use case is only about providing static context data to a partial.

Our Example: We have breadcrumbs that we sometimes render on the server and sometimes on the client. The first two breadcrumbs are always "Home" and "Back". So if we did this:

{{#each breadcrumbs}}
  {{>breadcrumb}}
{{/each}}

we would have to make sure that the "home" and "back" items are in the template context on the server and the client, basically duplicating code. With the include, we could instead write this template:

{{breadcrumb title="Home" url="http://example.com/"}}
{{breadcrumb title="I don't know my browser has a back button" url="javascript:history.back()"}}
{{#each breadcrumbs}}
  {{>breadcrumb}}
{{/each}}

Which would keep those two links shared in the template.