>
> 1)
> The "gridRendered" event is not picked up (in Preview filter) when
> there is no element in the dom with the data-behavior="Preview"
> attribute. (when the filter hasn't run)
> In assumed the filter Preview was registered and globally
> "listening" (to catch the fired event) even if the Preview filter has
> not been actively used yet (by some already declared element in the
> dom).
> So, to test it I added a dummy div to the dom (not associated to the
> list that is turned into the grid) with the data-behavior="Preview"
> attribute, which is silly of course...
> What's wrong with my thinking process?
>
Behavior filters are rendered in DOM order (so containers with filters have
their filters applied before their children, and siblings with filters have
theirs applied first child, then second, and so on). Filters are also
applied in the ordered they are listed, so if you have data-behavior="A B"
it will render A and then B. The biggest reason that the rule is that
filters can't know about each other is that the user of the filter shouldn't
have to know that A comes before B (or whatever) and it gets even more
complicated the more filters you add.
When you give an element a filter property, that filter's setup method is
invoked (the function you define; there's also a long-form version of a
filter that's an object with that function defined as the "setup" property).
Anyway, that function is never invoked if there is no element with that
filter. So if you don't have an element with data-behavior="Preview" your
function which adds the event listener will never be invoked. Make sense?
>
> 2)
> The Preview class (and thus the Behavior filter) is setup for one 1
> element basically. If I add data-behavior="Preview" to an element the
> filter is called and the class is instantiated.
> But in the code above I abuse the "gridRendered" event to call a
> preview() method on an array of elements I select with a css selector
> on the grid container (basically: all childs except empty cells).
> (the preview method call does: return new Preview(this, options) -
> pretty straightforward).
> This is of course wrong: I should not call the Element method
> preview() on multiple elements in a filter created to manage 1
> element.
> How should I "get this right"?
>
It seems to me that the "Preview" class is not a behavior filter. It's not
something in the DOM that gets decorated. Rather, it's something that gets
instantiated by your Grid class. Because you don't want your grid to have
knowledge of your preview class (instead opting to connect the two together
with events, which I think is appropriate), I see three options for you:
1. Create a super class that knows about Grid and Preview (GridPreview).
Create a filter for this.
2. Create a behavior that has the event hooks into the Grid that creates
previews (a behavior filter called GridPreview that has onComplete:
function(){ new Preview...} in the invocation of the grid class).
3. Have only one behavior filter (Grid) but an option that turns on
previews for the grid that, when true, adds these event hooks.
For filters to work right, they each have to do a thing on their own. Use
even arbitration when they need to coordinate their behavior. Thus a Preview
class that does it's own thing and works even if the Grid isn't there and
vice versa. Your DOM is decorated with BOTH of these things and the event
arbitration exists only to deal with the event that they are both in use on
the same DOM tree.
-a
