blackbird-promises

# Introduction

Blackbird is a fork of Bluebird, which is a fully featured promise library with focus on innovative features and performance. Blackbird adds new functions on top of the Bluebird API, but does not remove any.

Please see the bluebird website for further documentation, references and instructions. See the Bluebird API reference here.

Differences from Bluebird

Deep Context

Blackbird provides a mechanism for maintaining deep context through promise chains. This is like an omnipresent version of Promise.bind() -- it provides an environment that is not only shared by the current promise chain, but also by any subchains consisting of Blackbird promises.

We use deep context to store information collected in the top layers of our API (say, information about the currently logged-in user) as we call out to middleware layers that are themselves built on Blackbird promises.

This allows all the contextual information to be utilized seamlessly even by deeply-nested subsystems without worrying about lexical this or spaghetti argument passing, which in turn makes the subsystems more reusable.

Spec

The "deep context" of a promise is either:

• The deep context of its preceding promise, if it is the result of .thening another promise
• A shallow copy of the deep context of its parent promise, if it is the result of creating a promise inside of another promise's handler.
• An empty object, {}, otherwise.

setDeepContext

Promise.setDeepContext(object) -> undefined

Merges the given object (as if Object.assign()ed) with the deep context of the currently-running Promise.

getDeepContext

Promise.getDeepContext() -> object

Gets the deep context of the currently-running Promise. The deep context should be treated as immutable; use .setDeepContext to modify it.

License

The MIT License (MIT)

Copyright (c) 2013-2016 Petka Antonov Copyright (c) 2016 William C. Johnson

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.