Created
April 11, 2017 09:38
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Decorators to allow angular controller subclasses without knowing anything about dependencies of base class
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/** | |
* decorator especially for BaseController to block second call to its constructor. The constructor is invoked twice due to the | |
* trickery in the Controller decorator on any subclass of BaseController. The writer of that subclass will invoke | |
* `super()` in its constructor but we have to ignore this call to BaseController as the Controller decorator has already invoked | |
* BaseController with the required dependencies. | |
*/ | |
function ConstructOnce(): ClassDecorator { | |
return (c: ControllerConstructor) => { | |
const wrapped = function (this: BaseController, ...args: any[]) { | |
// only invoke constructor the first time, and ignore second (no-arg) call | |
if (this['$$constructed']) { return; } | |
this['$$constructed'] = true; | |
c.apply(this, args); | |
}; | |
__extends(wrapped, c); | |
return wrapped; | |
}; | |
} | |
type ControllerConstructor = new (...args: any[]) => BaseController; |
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/** | |
* decorator for a subclass of BaseController to ensure the dependencies of both the subclass constructor and the | |
* BaseController superclass are injected. This removes the need of the decorated subclass to know anything about the | |
* dependencies needed by the BaseController super class and even allows this super class to add additional dependencies | |
* without requiring any need to the subclass or the no-arg super call in its constructor. | |
* Example: | |
* ``` | |
* @Controller() | |
* class MyController extends BaseController { | |
* static $inject=['$log']; | |
* constructor(private $log: angular.ILogService) { | |
* super(); // assume the super class doesn't need any dependencies. The decorator will handle this. | |
* } | |
* } | |
* ``` | |
*/ | |
export function Controller(): ClassDecorator { | |
return (c: ControllerConstructor) => { | |
const ownInject = (c as Object).hasOwnProperty('$inject'); // does decorated class have its own $inject? (not from prototype) | |
const numInjects = ownInject ? c.$inject!.length : 0; // number of entries in $inject of decorated class | |
const wrapped = function (this: BaseController, ...args: any[]) { | |
// fist invoke BaseController constructor with "extra" arguments | |
BaseController.apply(this, args.slice(numInjects)); | |
// ...then invoke decorated class constructor with its own dependencies | |
c.apply(this, args.slice(0, numInjects)); | |
}; | |
__extends(wrapped, c); | |
// make $inject on wrapped class a combination of the $inject of the decorated class and the $inject of the base class | |
wrapped.$inject = ownInject ? c.$inject!.concat(BaseController.$inject) : BaseController.$inject; | |
return wrapped; | |
}; | |
} |
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