Example for abstract definition: "promise resolution procedure"

[BairDev]

Hi, I don't quite get the meaning of this sentence:

The promise resolution procedure is an abstract operation taking as input a promise and a value, which we denote as [...].

Can this mean something like (Pseudocode):

function(promise, x) {
   if (promise === x) {
      throw new TypeError();
   }  
   // do more stuff
}

If this is the case, does this function has anything to do with resolving a promise? To be more precise: what is the meaning of resolution?

[bergus]

Have a look at http://stackoverflow.com/questions/29268569/what-is-the-correct-terminology-for-javascript-promises Yes, resolution is exactly the substantive for resolving. To resolve a promise, you run the promise resolution procedure with a value x.

[BairDev]

Alright, thanks. I mainly was confused because of two points, both regarding the use of Promises in the AngularJS/$q context.

• $q.defer().resolve should actually be called $q.defer().fulfill. Am I right with this assumption?
• I've never seen an API like this: PromiseObject.resolve(promise, value). The Promise[Object].resolve method section of ECMAScript 2015 actually states, that promise is an internal slot of the PromiseObject.

But anyway, angular.$q might not follow the spec (this spec), then it is not a good example.

[ForbesLindesay]

The promise resolution procedure is an abstract operation. What this means is that it is a description of some functionality for use within the spec, rather than a function or method that should actually be exposed to users. Some promise implementations do have a function very similar to this one, many do not.

• $q.defer().resolve should internally run the promise resolution procedure with the promise attached to $q.defer() and the argument you pass to $q.defer().resolve.
• As I said, libraries don't expose the promise resolution procedure as a public method, but rather use it internally as an implementation detail.

[bergus]

$q.defer().resolve should actually be called $q.defer().fulfill. Am I right with this assumption?

No. resolve does not necessarily fulfill the promise. You can resolve with a rejected promise, leading to a rejection, or you can resolve with a never-settling promise, leading to nothing but the lock-in.

[BairDev]

Many thanks for the background stuff. I was not aware of this branch in $q.