Revert #3218, replace #4358. Deprecate global access from templates

[mixonic]

Replaces #4358. These deprecations are narrow in scope, and only impact {{Global}}. They do not deprecate any other global access in templates. Deprecating all global access from templates would a) need to be done helper-by-helper or b) would impact the get and binding code at a lower level.

@xtian I'm rewritten your first commit but preserved it here.

@ebryn yo.

[mixonic]

Bleh, this is probably not actually ready to go. There are many deprecation notices that fire in the logs during a test run now, an example:

Global lookup of TemplateTests.LabelView from a Handlebars template is deprecated.
Global lookup of Ember.Handlebars.EachView from a Handlebars template is deprecated.
Global lookup of Foo.bar from a Handlebars template is deprecated.
Global lookup of TemplateTests.CollectionView from a Handlebars template is deprecated.
Global lookup of TemplateTests.YieldingView from a Handlebars template is deprecated.

Looks like {{#view calls are impacted by that first commit. Opinions wanted: Should we clean up the usage of global view helper in tests, or not deprecate that behavior?

[xtian]

Sorry for being MIA and thanks for taking this over. This is a weird issue and I wasn't sure what to do with it.

#3218 was a small change that made {{Foo}} behave the same as all the helpers that use bindings (i.e., always look up Foo as a global).

I tried to explain in #4358, but it is not simple to invert that behavior. Many helpers use globals as you've seen, and most use bindings directly. There's currently no way to determine whether a binding is being created from a template vs app code.

I didn't think modifying the bindings code was great, but it was the only solution I could find. Anyway, I was missing something and didn't know how to get the tests to pass.

I do think only deprecating global lookup for {{Foo}} and {{#each Foo}} makes things more inconsistent because there are many other cases where global lookup can happen.

[mixonic]

@xtian definitely agree about deprecations being inconsistent only on lookup and #each. I think we could cover the other helpers without too much effort if that level of deprecation is what is needed here. @ebryn asked me to add these deprecations, but I'm not clear myself on what the long-term plan is (is it to remove global access from templates post 1.x?).

I prefer keeping this discussion focused on the templates though, and to avoid discussing anything lower-level until #4124 can be merged (since it may raise deprecations for some of the inconsistencies as well).

[mixonic]

@ebryn this deprecates direct global access and access via #each. It does not deprecate calls to resolveParams like the original, but I don't think that is required.

[oskarols]

@mixonic Do you mean it does not fix the issue where uppercase properties are resolved as globals?
I.e. having controller#NBAPlayer and using that with contentBinding=NBAPlayer when using a component in a template.
If so, should that be in a separate issue?

[mixonic]

@oskarols I'm confused by your example. This PR is only for deprecation of global access. Via {{Global}} and {{#each Global}}. No other access is changed.

[mixonic]

Newly rebased, I believe this is ready to go. /cc @ebryn this was something you asked for, let me know what you think of the implementation.

[mixonic]

@ebryn monthly yo. I could use feedback or a merge or a close. Freshly rebased.

[ebryn]

This deprecation shouldn't be fired if the path resolved locally. It's legit to have capitalized local paths. The behavior we're looking for is described here: #3218 (comment)

[mixonic]

This is not possible with how get works today. Get does the fallback internally. Short of calling get with the same path and Ember.lookup as the first argument, imo a deprecation as specific as you want won't happen.

[mixonic]

Oh wait, we have normalizePath. Maybe that can help.

[mixonic]

This is pretty good. Still a more deprecations firing from tests than I would prefer, but this is pretty close to ideal.