Passing events to (Athena) event handlers.
Hi all. In the thread entitled "How to insert an Athena event handler using Stan?" in October and November 2006, Jean-Paul Calderone said: """ The issue with the handler you showed me is most likely that the handler thinks its first argument is an event, but it is actually a node. There is no way to access the event object right now, but I have been considering just passing it as the next argument. """ and: """ [Though] this may shortly change to function doFoo(self, node, event) (which is completely backwards compatible, of course, due to the magic of javascript sucking so much). """ I've just hit this particular issue. Up until now all my events have been heavily node-based (e.g. tabbing out of a field, submitting a form, etc), where you can generally get away with just having access to the node the even happened on. However, not having access to the event itself renders handlers for events like 'onkeyup' almost useless, unless you register them with the top-level document (like the Nevow.Athena._checkEscape() works), and as far as I can tell it makes implementing certain things like drag and drop much more difficult. Is there a branch with experimental support for this? If not, I've been digging around in where I think the relevant code is, namely: Nevow/nevow/athena.py line 1062: _handlerFormat = "return Nevow.Athena.Widget.handleEvent(this, %(event)s, %(handler)s);" and: Nevow/nevow/js/Divmod/Runtime/__init__.js line 963: The Javascript looks like: Nevow.Athena.Widget.handleEvent = function handleEvent(node, eventName, handlerName) { var widget = Nevow.Athena.Widget.get(node); var method = widget[handlerName]; var result = false; if (method === undefined) { Divmod.msg("Undefined event handler: " + handlerName); } else { result = Nevow.Athena.Widget.dispatchEvent( widget, eventName, handlerName, function() { return method.call(widget, node); }); } return result; }; It looks like: 1. Adding an event argument to the handler format in the Python (I don't think that _rewriteEventHandlerToAttribute() needs modification); 2. Adding the corresponding 'event' argument to handleEvent() in the JS; 3. Adding IE hacks (using window.event instead of event, etc) to the start of handleEvent(); 4. Adding the event to the list of arguments of method.call() within the anonymous function passed as the fourth argument to dispatchEvent() would achieve this, and as JP pointed out, this should be backwards compatible, as no extant JS handler functions should be declaring additional arguments. Note that within dispatchEvent() itself the callable is invoked as callable.call(widget), but it looks like the 'widget' argument is ignored entirely by the anonymous function, which contains its own method call with its own "closure-y" arguments. Because of this I reckon dispatchEvent() needs no modification whatsoever. Would a patch posted as a trac ticket be acceptable? I searched trac for 'event' and couldn't find anything resembling this. What would the unit test requirements be for a change like this be? Thanks, Ricky
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