Re: [Adobe-source-devel] View concept singleton state

[Mat M. <mm...@em...>]

Hi Foster,

I think you already know my views on this, but I'll repeat them given =
that you initiated the wider discussion. First off, when I suggested =
that we might make use of the notion of a special state, the term that I =
used was "singular", not "singleton". As others pointed out, the two =
terms are not interchangeable.=20

At first I was considering adding a hook to any_view providers a chance =
to install a "wrong type" handler. But I soon began to sort my ideas =
out, and I set this aside when Sean said he would consider adding type =
constraints to the model. I never intended for protocol relating to =
singular to live in any_view. I sketched my reasons after I noticed that =
you had added such code to any_view, (before asking you to remove it). I =
explained my resistance in a bit more detail, offering a rationale =
similar to the one Sean gave above, after noticing that you added it =
back to any_view again (before asking you to remove it a second time). =
Can you say more about why you keep aiming to get singular protocol into =
any_view, especially in a world where, say, types could be checked in =
the model and the concrete view can choose as specific or as general a =
view_model_type as they wish?

- Mat

P.S. Does anyone know how we could get a review daemon installed on =
opensource.adobe.com? Subscriptions in user specs don't seem to work for =
me at the moment.

###

Foster wrote, in two messages:=20

> I think this makes a ton of sense. In all the cases I had=20
> considered, there was no way the widget would be able to=20
> display something reasonable with the invalid data. Your=20
> example of a graph-like widget made a lot of sense, as well=20
> as the notion of extracting as much worthwhile information as=20
> possible and putting it up for display. So, in light of that,=20
> I'd propose add a view concept API to something like:
>=20
> 	void singleton(const model_type& value);
>=20
> We might also want to have a nullary singleton function for=20
> the case when the widget is asked to display something it=20
> can't decipher. For example, an edit text field being asked=20
> to display an icon:
>=20
> 	void singleton();
>=20
> Thoughts?
>=20

> -----Original Message-----
> From: ado...@li...=20
> [mailto:ado...@li...] On=20
> Behalf Of Foster T. Brereton
> Sent: Tuesday, October 17, 2006 4:32 PM
> To: adobe-source developers; ASL Users
> Subject: [Adobe-source-devel] View concept singleton state
>=20
> Hey all,
>=20
> I wanted to email the group regarding something I'm=20
> implementing for the preset widget, because I think it can be=20
> lifted into the View Concept as a whole.
>=20
> A while back Mat and I were talking about the following=20
> problem: what is the proper behavior of a view when it is=20
> asked to display a value it cannot display? As an example,=20
> let us say I have an 'analog clock' =20
> display and it is asked to show the time 25:75. What should=20
> the clock do? To solve this, (thus far) we came up with the=20
> idea that every view should have a singleton state. The=20
> singleton state for a view is entirely=20
> implementation-specific; for instance in the clock example,=20
> the view could set itself to noon and make the clock have a=20
> red background -- something obvious to the user that says "I=20
> no longer accurately reflect the value in the model I have=20
> been asked to display". The instant the model communicates to=20
> the view a new value that it can display, the view should=20
> display the new value normally.
>=20
> The notion of a 'singleton value' does not exist, so the=20
> ability for the user to put a widget into the singleton state=20
> is prohibited. What would trigger the singleton value for a=20
> view usually takes the form of controller 'A' setting the=20
> value of a cell that view 'B' (also bound to the cell) cannot=20
> display. The value would be valid for A as a controller but=20
> not B as a view, so B reverts to the singleton state.
>=20
> Therefore, in the case when the view is also a controller=20
> (aka a widget), there is an additional requirement to be=20
> placed on the widget while in the singleton state. In=20
> addition to the above view requirement, the widget must also=20
> allow for valid user manipulation of the controller while=20
> displaying the singleton state. In the clock example above,=20
> (should the clock view be part of a clock widget), the=20
> singleton state should allow for the user to set another=20
> (valid) time (for example, by dragging the hands of the clock=20
> with the mouse).
>=20
> As a more concrete example, I am reworking the ASL preset=20
> widget so it models the View concept -- it is bound to a=20
> 'result' cell of the property model. When the result cell is=20
> updated, the preset widget compares its list of available=20
> presets against the result cell -- when a preset is found=20
> whose contents are a subset of the result cell, that preset=20
> is selected. The singleton state, then, occurs when the=20
> result cell is in a state for which no preset exists. The=20
> display behavior I am implementing is to append a menu item=20
> named "Custom" to the preset category list. This will still=20
> let the user select a new preset category from the preset=20
> category list, but at the same time clearly tells the user=20
> "the dialog as it stands matches no presets."
>=20
> Thoughts?
>=20
> Blessings,
> Foster
>=20
>=20
> --
> Foster T. Brereton              <=E1=BC=B0=CF=87=CE=B8=CF=8D=CF=82><   =
           Romans =20
> 3:21-26
> A d o b e   S o f t w a r e   T e c h n o l o g y   L a b
> "What 99 percent of programmers need to know is not how to=20
> build components but how to use them." -- Alexander Stepanov=20
> "Now we have very simple code and the meaning is perfectly clear. =20
> Drink the Kool-Aid" -- Sean Parent
>=20
>=20
> --------------------------------------------------------------
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> Using Tomcat but need to do more? Need to support web=20
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>=20