In template scope

[tmeasday]

Hey Chris,

This branch solves the problems I've seen with helpers + data not correct passing through to the content block of a Layout when used outside of IR.

It's quite a simple change really -- we remove the hacks that pass helper lookups through the Layout Component, and instead us the UI.InTemplateScope that already exists in Blaze.

What this does behind the scenes is wires the __content block up with the Layout component's parent as it's parent. Apparently this is OK, as this is exactly what happens when you use a template as a layout via a block helper inclusion + {{> UI.contentBlock}}.

There's only one downside to all this, and it might be a deal-breaker. I'm keen to hear you thoughts.

The problem is that because the content block is now short-circuited around the Layout, there doesn't appear to be any way to get contentFor to work. That's because it looks like this:

{{#with X}} // outer component
  {{#Layout}}
    // in here, the outer component is the parent
    {{#contentFor}} // so when we try to look up the closest ancestor Layout, it blows up.

Any ideas how to work around this? Otherwise, it seems like an ideal way to make helpers and data work in a rational, sensible way inside yielded regions.

[tmeasday]

We've also discussed both the helper and the data issue being solved by more flexibility in Blaze. I can probably live with waiting for that, but we should definitely keep this PR around until we get an alternative.

If you are attached to contentFor (probably, I personally don't use it ATM), and can't think of another way to make it work (hopefully you can!), don't spend too long looking at this for now.