REQUEST FOR FEEDBACK: `angular.component()` - default directive controller name

[petebacondarwin]

We should use a consistent default value for the name of a component's directive controller when it is attached to the scope. See #10007 (comment)

Currently we are defaulting to the canonical name of the component. This is not ideal as

a) component names can become long and unwieldy for use in a template
b) it is more complicated to automatically update the template to be used in Angular 2, where the context is the controller.

The criteria for the name are:

1. it must be the same for all components
2. it must start with $
3. it must be short (2-4 chars)

In addition the name should represent what is actually being published to the scope.

Some of previous suggestions include:

• vm - this is the commonly used name in many applications but the controller is not necessarily a "view model"
• $comp - this is the current suggestion from the team but can be confused with compare and is not that short
• $ctrl - this can be confused with input ConTRoL elements
• $this - the controller is not really this in the template, since the context is still actually the scope

[drpicox]

c) programmers are tempted to use isolate:false and access to ancestors controllers directly.

[petebacondarwin]

@drpicox - I am tempted to say that we ban isolate: false for components created using this helper.

[drpicox]

I agree, after considering this:

• isolate: true when restrict is 'E': for me they are truly components, in where $ctrl notation has full meaning
• isolate: false when restrict is 'A': for me they are decorators, a kind of enhancer of the existing components, in this case $ctrl collides so the current nomenclature it's fine

But I consider that the second case is better to do with directives, decorators are not frequent, usually low level, and not suited for juniors.

So probably is good idea to ban isolate: false.

In other track of thinking, about decorators, a function to get the controller of the 'E' component of the current entity should be good idea, specially to write generic decorators to deal with any current component (require forces to know in advance which controller is and you cannot use a kind of interface of what are you looking for).

[Narretz]

I like $cmp, but find $comp even better, because it's clearer.

[mgol]

I like $cmp, but find $comp even better, because it's clearer.

I like $comp. Whenever I see $cmp I think "compare".

[tabanliviu]

different suggestion: why not have the name of the component as the controller instance name?
ex: user-profile -> scope.userProfile

[mgol]

@tabanliviu That's how it's currently done on master but @petebacondarwin mentioned in this very issue, in the first post, why a common name is better.

[tabanliviu]

@mgol 👍 I think I glossed over that when I read the ticket. Should this change be considered more of a ngUpgrade issue? I think in the context of angular 1.x the current implementation is a good solution. Perhaps exposing this as a settings function that takes the component name and outputs the controller name? this way it serves the current pattern and a future migration path.

[vivainio]

Bikeshed time.

+1 for $ctrl.

Ctrl has lots of pre-existing culture in Angular 1 documentation and examples as the "controller" suffix. Try googling "angular ctrl" for good measure.

The current choice of deriving it from component name is quite nasty, as they indeed tend to get pretty long in real applications.