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Rearchitect Q for closure avoidance and WeakMap
Implement the `Promise` constructor. The promise constructor serves both as a deferred promise constructor that accepts a function, and a new kind of promise constructor that accepts a backing handler object. The backing handler object must implement `dispatch(resolve, op, operands)` and `inspect()`. The new promise constructor replaces the `Q.promise` function, which is deprecated. The new promise constructor replaces `makePromise`, which has been removed entirely. As such, Q-Connection will have to be rearchitected to provide a custom promise handler for remote objects instead of using `makePromise`. Fixes #346. Postpone calling `then` on a thenable until a message is dispatched to the coerced promise. Fixes #372. Fixes #369. When coercing a thenable, memoize the resulting promise to avoid re-starting a lazy promise. Add support for vicious cycle detection. Fixes #223. This change request also reviews the Q API, deprecating many interfaces that remain from legacy designs. Fixes #215. Factor most Node.js tools into `q/node` module. Mirror deprecated interfaces in Q. Support for `close` and `closed` has been removed from `Queue`, which has additional ramifications for Q-Connection. I intend to use Q-IO streams in Q-Connection instead of raw queues. Most of the Q specifications continue to work after these changes, but with many deprecation warnings. The specs have been revised to appease the deprecation warnings. :warning: However, the specifications for "progress" have all been disabled pending a closer investigation to decide whether to fix Q or fix the specs. The promise protocol no longer supports "set" and "delete" operations. Function application is a special case of "post", and for support of "fbind", it is now possible to pass a "thisp" as a final argument. The "when" message is now called simply "then". Support for pre-ECMAScript 5 has been abandoned outright, pending review. Removed: - Q.set, promise.set - Q.delete, promise.delete - Q.nearer - Q.master The following methods of `Q` are deprecated in favor of their equivalents on the `promise` prototype: - `progress`, `thenResolve`, `thenReject`, `isPending`, `isFulfilled`, `isRejected`, `dispatch`, `get`, `post`, `invoke`, `keys` Other deprecations: - Q.resolve in favor of Q - Q.fulfill in favor of Q - Q.isPromiseAlike in favor of Q.isThenable - Q.when in favor of Q().then - Q.fail and promise.fail in favor of promise.catch - Q.fin and promise.fin in favor of promise.finally - Q.mapply and promise.mapply in favor of promise.post - Q.send and promise.send in favor of promise.invoke - Q.mcall and promise.mcall in favor of promise.invoke - Q.promise in favor of new Q.Promise with a resolver function - Q.makePromise in favor of new Q.Promise with a handler object - promise.fbind in favor of Q.fbind - deferred.makeNodeResolver() in favor of require("q/node").makeNodeResolver(deferred.resolve) - promise.passByCopy() in favor of Q.passByCopy(promise), provisionally Node.js wrappers that have been moved into their own module have a deprecated interface in Q proper: - `nodeify`, `denodify`, `nfbind`, `nbind`, `npost`, `ninvoke` But the following experimental aliases are deprecated and do not exist in `q/node`: - `nsend` for `ninvoke` - `nmcall` for `ninvoke` - `nmapply` for `npost`
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,135 @@ | ||
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| var Q = require("./q"); | ||
| var NQ = exports; | ||
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| /** | ||
| * Creates a Node-style callback that will resolve or reject the deferred | ||
| * promise. | ||
| * @returns a nodeback | ||
| */ | ||
| NQ.makeNodeResolver = function (resolve) { | ||
| return function (error, value) { | ||
| if (error) { | ||
| resolve(Q.reject(error)); | ||
| } else if (arguments.length > 2) { | ||
| resolve(Array.prototype.slice.call(arguments, 1)); | ||
| } else { | ||
| resolve(value); | ||
| } | ||
| }; | ||
| }; | ||
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| /** | ||
| * Passes a continuation to a Node function, which is called with the given | ||
| * arguments provided as an array, and returns a promise. | ||
| * | ||
| * NQ.nfapply(FS.readFile, [__filename]) | ||
| * .then(function (content) { | ||
| * }) | ||
| * | ||
| */ | ||
| NQ.nfapply = function (callback, args) { | ||
| var deferred = Q.defer(); | ||
| var nodeArgs = Array.prototype.slice.call(args); | ||
| nodeArgs.push(NQ.makeNodeResolver(deferred.resolve)); | ||
| Q(callback).fapply(nodeArgs).catch(deferred.reject); | ||
| return deferred.promise; | ||
| }; | ||
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| /** | ||
| * Passes a continuation to a Node function, which is called with the given | ||
| * arguments provided individually, and returns a promise. | ||
| * @example | ||
| * Q.nfcall(FS.readFile, __filename) | ||
| * .then(function (content) { | ||
| * }) | ||
| * | ||
| */ | ||
| NQ.nfcall = function (callback /*...args*/) { | ||
| var args = Array.prototype.slice.call(arguments, 1); | ||
| return NQ.nfapply(callback, args); | ||
| }; | ||
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| /** | ||
| * Wraps a NodeJS continuation passing function and returns an equivalent | ||
| * version that returns a promise. | ||
| * @example | ||
| * Q.nfbind(FS.readFile, __filename)("utf-8") | ||
| * .then(console.log) | ||
| * .done() | ||
| */ | ||
| NQ.nfbind = | ||
| NQ.denodeify = function (callback /*...args*/) { | ||
| var baseArgs = Array.prototype.slice.call(arguments, 1); | ||
| return function () { | ||
| var nodeArgs = baseArgs.concat(Array.prototype.slice.call(arguments)); | ||
| var deferred = Q.defer(); | ||
| nodeArgs.push(NQ.makeNodeResolver(deferred.resolve)); | ||
| Q(callback).fapply(nodeArgs).catch(deferred.reject); | ||
| return deferred.promise; | ||
| }; | ||
| }; | ||
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| NQ.nbind = function (callback, thisp /*...args*/) { | ||
| var baseArgs = Array.prototype.slice.call(arguments, 2); | ||
| return function () { | ||
| var nodeArgs = baseArgs.concat(Array.prototype.slice.call(arguments)); | ||
| var deferred = Q.defer(); | ||
| nodeArgs.push(NQ.makeNodeResolver(deferred.resolve)); | ||
| function bound() { | ||
| return callback.apply(thisp, arguments); | ||
| } | ||
| Q(bound).fapply(nodeArgs).catch(deferred.reject); | ||
| return deferred.promise; | ||
| }; | ||
| }; | ||
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| /** | ||
| * Calls a method of a Node-style object that accepts a Node-style | ||
| * callback with a given array of arguments, plus a provided callback. | ||
| * @param object an object that has the named method | ||
| * @param {String} name name of the method of object | ||
| * @param {Array} args arguments to pass to the method; the callback | ||
| * will be provided by Q and appended to these arguments. | ||
| * @returns a promise for the value or error | ||
| */ | ||
| NQ.npost = function (object, name, nodeArgs) { | ||
| var deferred = Q.defer(); | ||
| nodeArgs.push(NQ.makeNodeResolver(deferred.resolve)); | ||
| Q(object).dispatch("post", [name, nodeArgs]).catch(deferred.reject); | ||
| return deferred.promise; | ||
| }; | ||
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| /** | ||
| * Calls a method of a Node-style object that accepts a Node-style | ||
| * callback, forwarding the given variadic arguments, plus a provided | ||
| * callback argument. | ||
| * @param object an object that has the named method | ||
| * @param {String} name name of the method of object | ||
| * @param ...args arguments to pass to the method; the callback will | ||
| * be provided by Q and appended to these arguments. | ||
| * @returns a promise for the value or error | ||
| */ | ||
| NQ.ninvoke = function (object, name /*...args*/) { | ||
| var nodeArgs = Array.prototype.slice.call(arguments, 2); | ||
| var deferred = Q.defer(); | ||
| nodeArgs.push(NQ.makeNodeResolver(deferred.resolve)); | ||
| Q(object).dispatch("post", [name, nodeArgs]).catch(deferred.reject); | ||
| return deferred.promise; | ||
| }; | ||
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| /** | ||
| * If a function would like to support both Node continuation-passing-style and | ||
| * promise-returning-style, it can end its internal promise chain with | ||
| * `nodeify(nodeback)`, forwarding the optional nodeback argument. If the user | ||
| * elects to use a nodeback, the result will be sent there. If they do not | ||
| * pass a nodeback, they will receive the result promise. | ||
| * @param object a result (or a promise for a result) | ||
| * @param {Function} nodeback a Node.js-style callback | ||
| * @returns either the promise or nothing | ||
| */ | ||
| NQ.nodeify = nodeify; | ||
| function nodeify(object, nodeback) { | ||
| return Q(object).nodeify(nodeback); | ||
| } | ||
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