[Laszlo-dev] designing API which is LZX friendlyand Javascript-friendly

[Henry Minsky]

What I am beginning to think is that there need to be two different
instantiation APIs
for components, one which is designed to be called from LZX (XML), which
does
a lot of "automagic" setup, and one designed to be called from script, which
exposes all
the individual steps as much as possible. So you can decide for example to
instantiate a
menu item before there is a parent to add it to, or if you need to add it to
a place in
the parent which isn't at the end of the current list of items.

Tucker has proposed using something besides "new" to create new components
in script. I think that is a good idea, but maybe we need to go one step
further and have some conventions for two different standard ways to
instantiate a component:

One way is the "LZX" way, where you pass a parent view, and an arglist, so
that "new MyFrob(...)" behaves as much as possible like using <MyFrob> in
LZX; as much magic as possible is done to install the object into it's
parent environment.

 And the other would be the "script" way, which behaves in a more modular
fashion, so you would expect to manually instantiate an
object, then add it to a parent or not at your discretion, and set callbacks
and event handlers, etc, manually.



On 11/29/05, Don Hopkins <dhopkins at donhopkins.com> wrote:
>
>  What are the advantages of dynamically creating user interface components
> through xml data binding, instead of using a JavaScript api?
>
>
>
> I've been playing around with pie menus for Laszlo, trying to come up with
> a Laszlish way to dynamically create and configure them.
>
>
>
> http://www.donhopkins.com/drupal/node/40
>
> http://www.donhopkins.com/lzxnet/my-apps/PieTest.lzx
>
> http://www.donhopkins.com/lzxnet/my-apps/PieTest.lzx?lzt=source
>
> http://www.donhopkins.com/lzxnet/my-apps/piemenu.lzx?lzt=source
>
>
>
> The Laszlo pie menus don't currently support an API for modifying the
> menus dynamically, but I've been thinking about how that should work, and
> how it could support user-editable menus that knew how to write themselves
> back out as XML.
>
>
>
> Some pie menus are dynamically generated from data, so all items are
> usually handled the same (or from a small set of pre-defined handlers based
> on the dataset), but other pie menus are designed by hand with custom
> handlers, tracking feedback and graphical resources associated with each
> item.
>
>
>
> One problem with only defining widgets from XML, is how do you attach
> custom methods and event handlers to widgets?
>
>
>
> Including custom JavaScript handlers and constraints in the widget xml
> definition would require a JavaScript compiler in the Flash player (but it
> would be possible in the DHTML version of Laszlo). You have to pre-define
> all the handlers and constraint expressions as named functions, refer to
> their names in the xml, and look them up at run-time.
>
>
>
>             -Don
>
>
>
>
>



--
Henry Minsky
Software Architect
hminsky at laszlosystems.com
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