Idea $this in directive locals calls

[jpolo]

It would be nice to have a normalized reference to the locals for directive expression.
I've proposed $this but other candidates could be better ($locals, etc...)

Example

angular.directive("fooBar", function () {

   return {
     scope: {
       ngCallback:"&"
     },
     compile: function ($scope) {
       var ctx = {
       foo: "bar"
       };
       ctx.$this = ctx;// Keep a reference to the locals

       $scope.ngCallback(ctx);
     }
   };
})

Allows to easily dump available locals

<foo-bar ng-callback="log($this)">

[Narretz]

Can you give a more complete example? I've a hard time figuring out the use case.

[jpolo]

The problem when passing just locals to the context is that there is no way to inspect all locals at once.
If log l is just a simple forward to console.log then log($this) would dump something like

{
  foo: "bar"
}

That helps a lot when using debugging/using light documented directives.

[petebacondarwin]

I think I see what you mean.

You want to have access to a single property on the scope that references the locals that were passed to through to the expression.
I.E. when we execute an expression we can provide some locals that are merged with the scope:

var someExpressionFn = $parse('someExpression');
someExpressionFn($scope, locals);

You would like us to automatically attach an additional property to the locals object that refers to the locals object itself.

[jpolo]

Exactly sir! Sorry if I wasn't clear before...

[petebacondarwin]

I see this as a rare requirement that can be easily implemented on a case by case basis as you show in your example @jpolo. I don't think it is something that we would want to add to all cases, especially as we would have to pollute the scope with yet another special property.

[petebacondarwin]

In general, if I have a load of things that I want to pass via locals that can be handled as a single thing by the client then I would set it up so:

$scope.ngCallback({ $event: ctx });

This (interestingly) is similar to the form that seems to be appearing in Angular 2 event handling.

[jpolo]

In my user need, I am the developer that uses a third party directive fooBar.
In your example, there is no programmatic way to know that the context local is named "$event" because I didn't write this code. My only solution is to read either the code or the doc if present but that is not always the case...

[petebacondarwin]

Sure, but the third party should document their directive, no?

[petebacondarwin]

Just to be clear, here is a plnkr: http://plnkr.co/edit/Hm0nWaybsJ8PxKsVQzIl?p=preview

[petebacondarwin]

What you are saying is that there is no programmatic way of enumerating the {a: 1, b: 2, c: 3} data.

[petebacondarwin]

I wonder if what we should say is that inside such an expression the this should refer to the merged "scope+locals" rather than just the scope? @lgalfaso what do you think?