Should we be using promises ? about google-maps-services-js HOT 5 CLOSED

@brendankenny @samthor ?

from google-maps-services-js.

OK, I had a play with what things look like with promises, and it's much nicer. Then I had a play with what things look like using window.fetch, and think this also makes a LOT of sense.

1. A lot of thought has gone into window.fetch and promises/A+, and so if our API looks like it, it will probably be well-design and pleasant to use. It will also feel familiar in years to come if window.fetch gets widespread adoption.
2. It makes the implementation of our client library much easier to read.

I've been injecting the fetch function, so that the developer can supply their own fetch polyfill (for browser or node). That feels quite natural. You have inject your API key as well, so the injection step had to happen anyway.

Injecting the fetch function will also allow people to unit test against our client library. According to Michael Feathers, this is "the golden rule of API design" (97 Things Every Programmer Should Know, 2010).

from google-maps-services-js.

Another issue with Promises and window.fetch(): how do you cancel?
AFAICT, the community hasn't decided how this should be done.

This is pretty important for us, since the client library offers to rate-limit and automatically retry.

• In my opinion, promises ought not be cancelled... that's an oxymoron. I'm not a fan of the back-pressure idea either. AND
• The fetch spec doesn't allow cancelling today. BUT
• Our client library request could be cancelled, because rate-limiting or retrying might mean we haven't yet called fetch().

Since our request function returns a promise, it will have to expose the cancelling mechanism via a revealing constructor. I imagine it looking like this:

var cancelGeocode;
googleMaps.geocode({address: 'Sydney Opera House'}, function(cancel) {
  cancelGeocode = cancel;
})
    .then(json)
    .then(function(response) {
      // do something
    });

// Meanwhile ...
if (weNoLongerNeedTheGeocode) {
  cancelGeocode();
}

Cancelling the request would reject the promise.

@juliaogris I'd appreciate your opinion too.

from google-maps-services-js.

I ought to mention too that calling cancel() can only be a hint. It doesn't guarantee that the Promise will be rejected.

from google-maps-services-js.

Closing this now since I think we've addressed everything here with the current state of the library.

from google-maps-services-js.