Extending the event system
<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi all,<div>I have 2 topics I am curious about, but will start a separate thread for the other one.</div><div>
</div><div>So, my question is, I want to tweak the event system to add some features, but I'm not sure if adding hooks to modify it is in the roadmap, or if the API is considered standard enough to extend.</div><div>
</div><div>Basically, there are some features that I would like to add:</div><div><b>1. Passing the scope of the event listener</b></div><div>We often have groups of methods that need to access common data that doesn't logically associate to just one DOM element.</div><div>I know the convention is to use closures, but this begins to add quite a bit to the memory footprint, especially when you have a lot of components, and in crappy but ubiquitous js engines (*cough*JScript*cough*).</div><div>I don't mean a partial apply, like Prototype's bind and bindAsEventListener, but just using a straight apply with the method and object that it should be scoped too.</div><div>I know for most common uses, it doesn't always make sense, but in large groups of applications the pennies become dollars pretty quickly.</div><div>
</div><div><b>2. Modifying the event object that's passed into the listener</b></div><div>I would like to add some custom helpers and constants to the event object that is passed into the listener, such as getXY() and ENTER, BACKSPACE (etc, where the keycodes are mapped to the constants), isChildOf(parentEl), etc.</div><div>
</div><div><b>3. Modifying the behavior of the event loop</b></div><div>Right now, if you return false from the loop, it does a event.stopPropagation() and event.preventDefault, but for custom events, I would like the behavior to completely halt the loop, and for events to be able to pass data between the listeners (which I think is already possible if you pass around an object).</div><div>
</div><div>I understand that a lot of these things just wouldn't make sense in the core, but I was wondering if there are plans to allow that sort of extension of the event system, or if the event api is safe enough to overwrite.</div><div>
</div><div>There are 2 things I would like to avoid, massive code duplication, and not being able to easily upgrade because the event system's API changed so drastically that upgrading would mean either massive refactoring on our part, or monstrous code duplication to emulate old behavior.</div><div>
</div><div>So, would you guys consider it safe enough to extend, are there existing plans, or are there existing ways to handle the methods above?</div><div>
</div><div>Thanks in advance for reading through all of this, and I appreciate any and all responses :)</div><div>
<div> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12px; "><div><div>
<b>Nate Cavanaugh</b></div><div>Director of User Interface Engineering</div><div>Liferay, Inc.</div><div>Enterprise. Open Source. For life.</div></div><div>
</div></span></div></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"> </div>
</div>
<div> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12px; "><div><div>
<b>Nate Cavanaugh</b></div><div>Director of User Interface Engineering</div><div>Liferay, Inc.</div><div>Enterprise. Open Source. For life.</div></div><div>
</div></span></div></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"> </div>
</div><div>So, my question is, I want to tweak the event system to add some features, but I'm not sure if adding hooks to modify it is in the roadmap, or if the API is considered standard enough to extend.</div><div>
</div><div>Basically, there are some features that I would like to add:</div><div><b>1. Passing the scope of the event listener</b></div><div>We often have groups of methods that need to access common data that doesn't logically associate to just one DOM element.</div><div>I know the convention is to use closures, but this begins to add quite a bit to the memory footprint, especially when you have a lot of components, and in crappy but ubiquitous js engines (*cough*JScript*cough*).</div><div>I don't mean a partial apply, like Prototype's bind and bindAsEventListener, but just using a straight apply with the method and object that it should be scoped too.</div><div>I know for most common uses, it doesn't always make sense, but in large groups of applications the pennies become dollars pretty quickly.</div><div>
</div><div><b>2. Modifying the event object that's passed into the listener</b></div><div>I would like to add some custom helpers and constants to the event object that is passed into the listener, such as getXY() and ENTER, BACKSPACE (etc, where the keycodes are mapped to the constants), isChildOf(parentEl), etc.</div><div>
</div><div><b>3. Modifying the behavior of the event loop</b></div><div>Right now, if you return false from the loop, it does a event.stopPropagation() and event.preventDefault, but for custom events, I would like the behavior to completely halt the loop, and for events to be able to pass data between the listeners (which I think is already possible if you pass around an object).</div><div>
</div><div>I understand that a lot of these things just wouldn't make sense in the core, but I was wondering if there are plans to allow that sort of extension of the event system, or if the event api is safe enough to overwrite.</div><div>
</div><div>There are 2 things I would like to avoid, massive code duplication, and not being able to easily upgrade because the event system's API changed so drastically that upgrading would mean either massive refactoring on our part, or monstrous code duplication to emulate old behavior.</div><div>
</div><div>So, would you guys consider it safe enough to extend, are there existing plans, or are there existing ways to handle the methods above?</div><div>
</div><div>Thanks in advance for reading through all of this, and I appreciate any and all responses :)</div><div>
<div> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12px; "><div><div>
<b>Nate Cavanaugh</b></div><div>Director of User Interface Engineering</div><div>Liferay, Inc.</div><div>Enterprise. Open Source. For life.</div></div><div>
</div></span></div></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"> </div>
</div>
<div> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12px; "><div><div>
<b>Nate Cavanaugh</b></div><div>Director of User Interface Engineering</div><div>Liferay, Inc.</div><div>Enterprise. Open Source. For life.</div></div><div>
</div></span></div></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"> </div>
Topic Participants
nate
Dave Methvin