Proposal : Bluebird.retry(), Bluebird.while(), Bluebird.or()

[lchenay]

When working in bluebird, i find those 3 extensions very usefull. I am the only one? Is it worth it I to take some time to clean them to match Bluebird convention, add tests and make a PR to add them in bluebird?

import Bluebird from 'bluebird';

// Retry a function N times, with a delay in case of fail
Bluebird.retry = function(fn, nbRetry, delayBetween) {
    return Bluebird.try(() => {
       return fn();
    }).catch((err) => {
        if (nbRetry == 0) {
            throw err;
        }
        return Bluebird.delay(delayBetween).then(() => {
            return Bluebird.retry(fn, --nbRetry, delayBetween);
        });
    });
};

// A async version of a while() in bluebird
Bluebird.while = function(condition, action) {
    const resolver = Bluebird.defer();
    const loop = function() {
        if (!condition()) return resolver.resolve();
        return Promise.cast(action())
            .then(loop)
            .catch((err) => {resolver.reject(err)});
    };

    process.nextTick(loop);
    return resolver.promise;
};

// or() implementation in Bluebird. 
// Allowing for exemple 
// this.getFromCache()
//   .or(() => this.getFromDb())
//   .or(() => this.getFromFlyingBird())
//   .or(() => this.getEmptyState())
//   .then((result) => this.displayResult());
Bluebird.prototype.or = function(fn) {
    return this.then((result) => {
        if (result) {
            return result;
        }

        return fn();
    })
};