angular/angular.js — pull request #7486 by lgalfaso (2014-05-16 13:53:43+00:00)
Title: feat(parse): ability to bind once an expressions

Expressions that start with `::` will be binded once. The rule
that binding follows is that the binding will take the first
not-undefined value at the end of a `$digest` cycle.

Watchers from `$watch`, `$watchCollection` and `$watchGroup` will
automatically stop watching when the expression(s) are bind-once
and fulfill.

Watchers from text and attributes interpolations will
automatically stop watching when the expressions are fulfill.

All directives that use `$parse` for expressions will automatically
work with bind-once expressions as long as they are evaluated
over a `$scope`. E.g.

```html

{{::item.name}};

```

Have fun