Add transform for ES7 decorators

[SaladFork]

The Ember 2.0 release blog post states:

As the JavaScript decorator proposal stabilizes, and as transpilers improve their implementations, we plan to adapt computed properties and other APIs to that syntax

Additionally, thanks to rwjblue/ember-computed-decorators, we can start using ES7 decorators in Ember apps today.

I thought I'd try to get a head start and as an exercise for learning AST transforms try and implement an ember-watson command for this transformation today. I've made some progress in my fork, but am hitting a roadblock:

• The esprima parser that is used by default cannot handle ES7 decorators:

Error: Line 4: Unexpected token ILLEGAL

• If I try switching to the babel parser, it seems unable to handle ES6:

AssertionError: did not recognize object of type "ExportDefaultDeclaration"

Any direction for addressing this would be most appreciated 😄

[marcioj]

These issues with decorators were fixed upstream. I think that converting the computed properties for the decorator syntax would be a create addition.

[SaladFork]

Awesome, thanks for the heads up!

Todo:

• Ember.computed -> @computed
  • without dependent keys
  • with dependent keys
    • should replace .get lookups when possible
    • should warn if argument names clash with any variable names in function
    • should probably suggest manual inspection as new arguments can now be used
    • What to do about expanded props like foo.@each.bar or foo.[]?
  • with get/set functions
  • should leverage convert-prototype-extensions for .property() ->> @computed

Do we want these? In the same command or separately?

• .readOnly() -> @readOnly
• Ember Data
  • DS.attr -> @attr
    • without arguments
    • with arguments: type ('string'), options hash ({ defaultsTo: ... })
  • DS.hasMany -> @hasMany
  • DS.belongsTo -> @belongsTo
• Ember.on -> @on
  • should leverage convert-prototype-extensions for .on() ->> @on
• Ember.observer -> @observes
  • should leverage convert-prototype-extensions for .observes() ->> @observes
• Other computed macros provided by ember-computed-macros such as @alias

Will put these in first comment to track progress once we decide what to include.

[elbeezi]

Do we want these?

yes. 👍