The callback paradigm could still be a convenient option. There definitely are times when a single listener is all you need.
- Josh On Tue, Jul 5, 2016 at 7:08 AM, Harbs <harbs.li...@gmail.com> wrote: > OK. I’ll leave it an EventDispatcher. But, should we try to emulate the > callback paradigm in addition? > > On Jul 5, 2016, at 3:07 PM, Josh Tynjala <joshtynj...@gmail.com> wrote: > > > There have been multiple cases where a developer decided to use callbacks > > instead of events in their API because they felt that no one would ever > > need multiple listeners, and I ended up actually needing them. The > > workarounds required can be ugly. Having been there, I try to avoid > making > > assumptions like that in my own code. > > > > Just my personal experience. > > > > - Josh > > On Jul 5, 2016 3:25 AM, "Harbs" <harbs.li...@gmail.com> wrote: > > > >> I’d like to start a discussion on what I did here. > >> > >> There is a pretty popular pattern in Javascript which allows for > chaining > >> of callbacks. Instead of lots of addEventListeners and such, you would > do > >> myClass.doSomething().success(handleSuccess).error(handleError). It’s > >> currently giving the class object to the handler, but it could take an > >> event object instead. I’m not sure what makes more sense. > >> > >> You can also specify things like myClass.onError = handleError. > >> > >> This approach works very well when there’s a single object which needs > the > >> callbacks. For those types of situations, EventDispatcher is not really > >> necessary at all. I’m thinking of removing the dependency on > >> EventDispatcher completely for URLLoader and related classes. Requiring > >> clients to call add and removeEventListeners is cumbersome and > error-prone. > >> > >> Thoughts? > >> > >> Harbs > >> > >> On Jul 5, 2016, at 1:09 PM, ha...@apache.org wrote: > >> > >>> Repository: flex-asjs > >>> Updated Branches: > >>> refs/heads/develop cc22300be -> 298d2041f > >>> > >>> > >>> Added callbacks > >>> > >>> > >>> Project: http://git-wip-us.apache.org/repos/asf/flex-asjs/repo > >>> Commit: > http://git-wip-us.apache.org/repos/asf/flex-asjs/commit/298d2041 > >>> Tree: http://git-wip-us.apache.org/repos/asf/flex-asjs/tree/298d2041 > >>> Diff: http://git-wip-us.apache.org/repos/asf/flex-asjs/diff/298d2041 > >>> > >>> Branch: refs/heads/develop > >>> Commit: 298d2041ff2c02c203764ed22fb11e131e4b092e > >>> Parents: cc22300 > >>> Author: Harbs <ha...@in-tools.com> > >>> Authored: Tue Jul 5 13:09:05 2016 +0300 > >>> Committer: Harbs <ha...@in-tools.com> > >>> Committed: Tue Jul 5 13:09:05 2016 +0300 > >>> > >>> ---------------------------------------------------------------------- > >>> .../flex/org/apache/flex/net/URLBinaryLoader.as | 37 +++++++-- > >>> .../main/flex/org/apache/flex/net/URLLoader.as | 78 ++++++++++++++++++ > >>> .../main/flex/org/apache/flex/net/URLStream.as | 86 > +++++++++++++++++++- > >>> 3 files changed, 191 insertions(+), 10 deletions(-) > >>> ---------------------------------------------------------------------- > >>> > >>> > >>> > >> > http://git-wip-us.apache.org/repos/asf/flex-asjs/blob/298d2041/frameworks/projects/Network/src/main/flex/org/apache/flex/net/URLBinaryLoader.as > >>> ---------------------------------------------------------------------- > >>> diff --git > >> > a/frameworks/projects/Network/src/main/flex/org/apache/flex/net/URLBinaryLoader.as > >> > b/frameworks/projects/Network/src/main/flex/org/apache/flex/net/URLBinaryLoader.as > >>> index 2dfc490..ff9121b 100644 > >>> --- > >> > a/frameworks/projects/Network/src/main/flex/org/apache/flex/net/URLBinaryLoader.as > >>> +++ > >> > b/frameworks/projects/Network/src/main/flex/org/apache/flex/net/URLBinaryLoader.as > >>> @@ -20,7 +20,6 @@ package org.apache.flex.net > >>> { > >>> > >>> import org.apache.flex.events.Event; > >>> - import org.apache.flex.events.EventDispatcher; > >>> import org.apache.flex.events.ProgressEvent; > >>> import org.apache.flex.utils.BinaryData; > >>> > >>> @@ -73,43 +72,63 @@ package org.apache.flex.net > >>> { > >>> super(); > >>> stream = new URLStream(); > >>> - stream.addEventListener(HTTPConstants.COMPLETE, > onComplete); > >>> + stream.addEventListener(HTTPConstants.COMPLETE, > >> completeHandler); > >>> } > >>> > >>> + /** > >>> + * Makes the URL request. > >>> + * > >>> + * @langversion 3.0 > >>> + * @playerversion Flash 10.2 > >>> + * @playerversion AIR 2.6 > >>> + * @productversion FlexJS 0.7.0 > >>> + */ > >>> public function load(request:URLRequest):void > >>> { > >>> stream.load(request); > >>> } > >>> > >>> + /** > >>> + * Cancels the URL request > >>> + * > >>> + * @langversion 3.0 > >>> + * @playerversion Flash 10.2 > >>> + * @playerversion AIR 2.6 > >>> + * @productversion FlexJS 0.7.0 > >>> + */ > >>> public function close():void > >>> { > >>> stream.close(); > >>> + //TODO do we need a callback for camceling? > >>> } > >>> > >>> - private function redirectEvent(event:Event):void > >>> - { > >>> - dispatchEvent(event); > >>> - } > >>> - > >>> - private function onComplete(event:Event):void > >>> + private function completeHandler(event:Event):void > >>> { > >>> data = stream.response; > >>> if (data) > >>> { > >>> dispatchEvent(event); > >>> + if(onComplete) > >>> + onComplete(this); > >>> + > >>> } > >>> else > >>> { > >>> // TODO dipatch error event? > >>> dispatchEvent(new Event(HTTPConstants.IO_ERROR)); > >>> + if(onError) > >>> + onError(this); > >>> } > >>> + cleanupCallbacks(); > >>> } > >>> > >>> - private function onProgress(event:ProgressEvent):void > >>> + private function progressHandler(event:ProgressEvent):void > >>> { > >>> this.bytesLoaded = event.current > >>> this.bytesTotal = event.total; > >>> dispatchEvent(event); > >>> + if(onProgress) > >>> + onProgress(this); > >>> } > >>> } > >>> } > >>> > >>> > >> > http://git-wip-us.apache.org/repos/asf/flex-asjs/blob/298d2041/frameworks/projects/Network/src/main/flex/org/apache/flex/net/URLLoader.as > >>> ---------------------------------------------------------------------- > >>> diff --git > >> > a/frameworks/projects/Network/src/main/flex/org/apache/flex/net/URLLoader.as > >> > b/frameworks/projects/Network/src/main/flex/org/apache/flex/net/URLLoader.as > >>> index 809e120..102f525 100644 > >>> --- > >> > a/frameworks/projects/Network/src/main/flex/org/apache/flex/net/URLLoader.as > >>> +++ > >> > b/frameworks/projects/Network/src/main/flex/org/apache/flex/net/URLLoader.as > >>> @@ -86,5 +86,83 @@ package org.apache.flex.net > >>> { > >>> throw new Error("URLLoader should not be > >> instantiated. Use a derived class instead.") > >>> } > >>> + > >>> + protected function cleanupCallbacks():void > >>> + { > >>> + onComplete = null; > >>> + onError = null; > >>> + onProgress = null; > >>> + } > >>> + /** > >>> + * Callback for complete event. > >>> + * > >>> + * @langversion 3.0 > >>> + * @playerversion Flash 10.2 > >>> + * @playerversion AIR 2.6 > >>> + * @productversion FlexJS 0.7.0 > >>> + */ > >>> + public var onComplete:Function; > >>> + > >>> + /** > >>> + * Callback for error event. > >>> + * > >>> + * @langversion 3.0 > >>> + * @playerversion Flash 10.2 > >>> + * @playerversion AIR 2.6 > >>> + * @productversion FlexJS 0.7.0 > >>> + */ > >>> + public var onError:Function; > >>> + > >>> + /** > >>> + * Callback for progress event. > >>> + * > >>> + * @langversion 3.0 > >>> + * @playerversion Flash 10.2 > >>> + * @playerversion AIR 2.6 > >>> + * @productversion FlexJS 0.7.0 > >>> + */ > >>> + public var onProgress:Function; > >>> + > >>> + /** > >>> + * Convenience function for complete event to allow > >> chaining. > >>> + * > >>> + * @langversion 3.0 > >>> + * @playerversion Flash 10.2 > >>> + * @playerversion AIR 2.6 > >>> + * @productversion FlexJS 0.7.0 > >>> + */ > >>> + public function complete(callback:Function):URLLoader > >>> + { > >>> + onComplete = callback; > >>> + return this; > >>> + } > >>> + > >>> + /** > >>> + * Convenience function for error event to allow > chaining. > >>> + * > >>> + * @langversion 3.0 > >>> + * @playerversion Flash 10.2 > >>> + * @playerversion AIR 2.6 > >>> + * @productversion FlexJS 0.7.0 > >>> + */ > >>> + public function error(callback:Function):URLLoader > >>> + { > >>> + onError = callback; > >>> + return this; > >>> + } > >>> + > >>> + /** > >>> + * Convenience function for progress event to allow > >> chaining. > >>> + * > >>> + * @langversion 3.0 > >>> + * @playerversion Flash 10.2 > >>> + * @playerversion AIR 2.6 > >>> + * @productversion FlexJS 0.7.0 > >>> + */ > >>> + public function progress(callback:Function):URLLoader > >>> + { > >>> + onProgress = callback; > >>> + return this; > >>> + } > >>> } > >>> } > >>> \ No newline at end of file > >>> > >>> > >> > http://git-wip-us.apache.org/repos/asf/flex-asjs/blob/298d2041/frameworks/projects/Network/src/main/flex/org/apache/flex/net/URLStream.as > >>> ---------------------------------------------------------------------- > >>> diff --git > >> > a/frameworks/projects/Network/src/main/flex/org/apache/flex/net/URLStream.as > >> > b/frameworks/projects/Network/src/main/flex/org/apache/flex/net/URLStream.as > >>> index 7b5ff89..e2b1654 100644 > >>> --- > >> > a/frameworks/projects/Network/src/main/flex/org/apache/flex/net/URLStream.as > >>> +++ > >> > b/frameworks/projects/Network/src/main/flex/org/apache/flex/net/URLStream.as > >>> @@ -107,6 +107,9 @@ package org.apache.flex.net > >>> protected function flash_complete(event:flash.events.Event):void > >>> { > >>> dispatchEvent(new > >> org.apache.flex.events.Event(HTTPConstants.COMPLETE)); > >>> + if(onComplete) > >>> + onComplete(); > >>> + cleanupCallbacks(); > >>> } > >>> COMPILE::SWF > >>> protected function > >> flash_progress(event:flash.events.ProgressEvent):void > >>> @@ -129,6 +132,9 @@ package org.apache.flex.net > >>> if (xhr.readyState == 4 && xhr.status == 200) > >>> { > >>> dispatchEvent(new > >> org.apache.flex.events.Event(HTTPConstants.COMPLETE)); > >>> + if(onComplete) > >>> + onComplete(); > >>> + cleanupHandlers(); > >>> }else if (xhr.readyState==4&&xhr.status==404){ > >>> // dispatchEvent(new > >> IOErrorEvent(IOErrorEvent.IO_ERROR)); > >>> } > >>> @@ -146,9 +152,87 @@ package org.apache.flex.net > >>> } > >>> > >>> //TODO send an event that it's been aborted > >>> + > >>> + cleanupCallbacks(); > >>> + > >>> } > >>> + private function cleanupCallbacks():void > >>> + { > >>> + onComplete = null; > >>> + onError = null; > >>> + onProgress = null; > >>> + } > >>> + /** > >>> + * Callback for complete event. > >>> + * > >>> + * @langversion 3.0 > >>> + * @playerversion Flash 10.2 > >>> + * @playerversion AIR 2.6 > >>> + * @productversion FlexJS 0.7.0 > >>> + */ > >>> public var onComplete:Function; > >>> + > >>> + /** > >>> + * Callback for error event. > >>> + * > >>> + * @langversion 3.0 > >>> + * @playerversion Flash 10.2 > >>> + * @playerversion AIR 2.6 > >>> + * @productversion FlexJS 0.7.0 > >>> + */ > >>> public var onError:Function; > >>> - } > >>> + > >>> + /** > >>> + * Callback for progress event. > >>> + * > >>> + * @langversion 3.0 > >>> + * @playerversion Flash 10.2 > >>> + * @playerversion AIR 2.6 > >>> + * @productversion FlexJS 0.7.0 > >>> + */ > >>> + public var onProgress:Function; > >>> + > >>> + /** > >>> + * Convenience function for complete event to allow > >> chaining. > >>> + * > >>> + * @langversion 3.0 > >>> + * @playerversion Flash 10.2 > >>> + * @playerversion AIR 2.6 > >>> + * @productversion FlexJS 0.7.0 > >>> + */ > >>> + public function > >> complete(callback:Function):org.apache.flex.net.URLStream > >>> + { > >>> + onComplete = callback; > >>> + return this; > >>> + } > >>> + > >>> + /** > >>> + * Convenience function for error event to allow > chaining. > >>> + * > >>> + * @langversion 3.0 > >>> + * @playerversion Flash 10.2 > >>> + * @playerversion AIR 2.6 > >>> + * @productversion FlexJS 0.7.0 > >>> + */ > >>> + public function > >> error(callback:Function):org.apache.flex.net.URLStream > >>> + { > >>> + onError = callback; > >>> + return this; > >>> + } > >>> + > >>> + /** > >>> + * Convenience function for progress event to allow > >> chaining. > >>> + * > >>> + * @langversion 3.0 > >>> + * @playerversion Flash 10.2 > >>> + * @playerversion AIR 2.6 > >>> + * @productversion FlexJS 0.7.0 > >>> + */ > >>> + public function > >> progress(callback:Function):org.apache.flex.net.URLStream > >>> + { > >>> + onProgress = callback; > >>> + return this; > >>> + } > >>> +} > >>> } > >>> > >>> > >> > >> > >
