On Wed, 30 May 2007 12:58:48 +0300, kgi <iacovou@gmail.com> wrote:
On Wednesday 30 May 2007 02:25:23 Jean-Paul Calderone wrote:
On Wed, 30 May 2007 01:44:07 +0300, kgi <iacovou@gmail.com> wrote:
Hi Jean-Paul; thanks yet again for chiming in with a timely response.
This is like trying to call an unbound method in Python. What you really want to be doing is calling chain on an /instance/ of XCall.B, not on the class object itself.
I see what you mean. I *thought* I was just mimicking the approach used in lots of the Nevow code itself, but now I see The Error Of My Ways. Just to make sure that my insight is not bogus, can you comment on the "truthiness" of the following statements:
Sure.
1. When a LiveElement is rendered, it is assigned an Athena Id (probably server-side) and something in the Nevow runtime creates a class *instance*, identifiable and accessible from the server through the magic of the Athena Id. In other words, there is rarely (never?) direct instantiation in JS code of objects ("var f = new Foo()") when the classes are Athena subclasses.
Yep. To be specific, "Nevow.Athena.Widget subclasses", though I don't think there are any other interested classes in the Nevow.Athena namespace. ;)
2. If I instantiated N LiveElements of the same class, all N would be individually accessible from the server just by calling object.callRemote().
Right. Each server-side LiveElement instance is tangled up with its corresponding client-side Nevow.Athena.Widget (subclass) instance, and vice versa.
3. However, whereas server->client calls have implicit access to the Athena Id, so the callRemote() can be routed accordingly to the right instance, client-side Javascript doesn't have this.
Roughly correct, but see below.
I think I was confused by the fact that up until now I've only been having one LiveElement instance of each type on a page, so I never had to think about object disambiguation.
If this is the case, then I need a way of informing *client* side objects how to find each other. In other words, I need to embed the callee javascript object's Athena Id into the caller, either at creation time, or later. Is this a "done thing"?
(Either that, or I go via the server)
Widgets on the client have a hierarchical relationship with each other which reflects the hierarchical relationship of their corresponding server-side LiveElement progenitors. That is, if LiveElement B has setFragmentParent called on it with LiveElement A as an argument, then Widget B will have a widgetParent property which refers to Widget A; similarly, Widget A's childWidgets array property will include widget B. These relationships can be used to pass messages between widgets in the browser without involving the server.
Also, I'd recommend not clobbering XCall.A and XCall.B with your class objects, since those are set up to be module objects because they each have a corresponding .js file. Athena's module system tries to mimick many aspects of Python's - in this case, XCall corresponds to a package, XCall.A and XCall.B are modules in that package, and you want to be defining things like XCall.A.Foo and XCall.B.Bar as attributes of those modules.
Ah, I see. You mean that the very existence of the files XCall/A.js sets up the (empty?) XCall.A namespace, and within XCall.A.js I define classes like:
XCall.A.Foo = Nevow.Athena.Widget.subclass ( 'XCall.A.Foo' );
Yep.
Thanks again for your help, Jean-Paul, I know how busy you guys are. I'm sorry if it takes two or three attempts to get my head round some of the muddier aspects of how it all fits together - it's all pretty new and unfamiliar.
No problem. :) Hope this helps, Jean-Paul