Add vicious cycle and self-resolution detection #223
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Vicious cycle detection would entail a check in deferred.resolve(value) to verify that Q.resolve(value).mostResolved() is not equal to deferred. |
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This is a small backward-compat hazard; tagging it as such. Also I'd like to point out that the upcoming Promises/A+ 1.1 revision requires self-resolution detection. (It encourages, but does not mandate, vicious cycle detection.) Search for "if x and promise" at https://github.com/promises-aplus/promises-spec. |
kriskowal
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Oct 21, 2013
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. 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`
kriskowal
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Oct 30, 2013
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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This seems like a better solution to the test case in #221.
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