[Dev] Re: mixinAClass vs Query

[Ted Leung]

On Jun 14, 2004, at 2:47 PM, Donn Denman wrote:

> Ted,
>
> In my example I'm actaully looking for the set of possible values that 
> an enumeration can have.
> Here's an example: various people want to add their own attributes to 
> the Contacts list.  Sara wants to add "golf handicap", Wayne wants to 
> add "bridge partner", and I want to add "eye color", etc.  We want to 
> be able to use an "Attribute Block" that presents an editor that's 
> appropriate for the Kind of the newly added attribute.  The golf 
> handicap is a number, so it could present an edit text field.  Maybe 
> bridge partner would support dragging another contact and dropping it 
> onto the attribute.  For eye color, we want a ComboBox that shows the 
> possible values for eye color: blue, green, grey, brown, etc.
> For "eye color" we'd need to query the schema and ask it the vaules 
> defined by the enumeration.   It was unclear to me that queries would 
> support this, or that you would want them to.  I think of queries as 
> always returning Items, but that's probably not right.
> Anyway this "Chamelian Block" seems like a useful thing because it 
> would be so general purpose.  Do you think a query would handle these 
> cases?

Okay, your example helps.  Two points -- 1) it's probably possible to 
have a query return a set of things that are not items, but that's 
probably down the road if we decide to do it at all. 2) I agree that we 
probably don't want o use a query to ask for the possible values of an 
enumeration.  But it may make sense to have some reasonable API for 
doing that.

>
> - Donn
>
>
> Ted Leung wrote:
>
>> As far as the query part of the discussion goes, I'm not sure what 
>> Donn is saying that queries don't return enumeration values.  The 
>> Query class that we have today doesn't, but there's no reason why a 
>> query shouldn't be able to return any attribute value of an item, 
>> even if the type of the attribute is Enum.   That aside, I'm not sure 
>> that you'd necessarily want to use a query to do what you are 
>> discussing here.  If you could imagine writing a query that returns 
>> all Blocks that have a particular (Enumeration) attribute value, then 
>> that would be (in my opinion) an appropriate use of a query.
>>
>> Ted
>>
>> On Jun 11, 2004, at 12:53 PM, John Anderson wrote:
>>
>>> Very interesting.
>>>
>>> I think it would be quite useful to have an AttributeBlock that just 
>>> displays any attribute and presents the appropriate U/I for whatever 
>>> type the attribute happens to be. I think that's what I'm going to 
>>> want for editing elements of the summary view. I like the idea 
>>> getting away from specific kinds of blocks and replacing them with a 
>>> more general purpose block, which might choose a natural default 
>>> based on the type of attribute, but also have a style attribute 
>>> which forces how the data is presented. This sounds so cool it makes 
>>> me want to go write it :-)
>>>
>>> John
>>>
>>> Donn Denman wrote:
>>>
>>>> John,
>>>>
>>>> It occurs to me that the mixinAClass/Attribute approach of 
>>>> attaching behavior to Blocks acts a little like a query, in that it 
>>>> populates the block, but appears to be much more flexible.  For 
>>>> instance, I'd like to make a ComboBoxAttribute block that points to 
>>>> an Attribute whose value is an Enum.  It would populate the 
>>>> ComboBox from the different values available in the Enumeration, 
>>>> and select the current value held by the Attribute.  I don't think 
>>>> you can do this with a query, since Enumeration values are not 
>>>> returned by queries.
>>>> I think in the long run we want a more general AttirbuteBlock that 
>>>> looks at the type of the attibute to be displayed, and then takes 
>>>> on the actual block kind appropriate for that attribute.  If the 
>>>> attribute was a boolean, it would present a check box.  String 
>>>> attributes would be displayed in static or edit text blocks.  
>>>> Comboboxes for Enumerations, etc.
>>>>
>>>> Just food for thought.  I think I'm going to plow ahead with the 
>>>> MarkupBar while we ponder AttributeBlocks.
>>>>
>>>> - Donn
>>>
>>>
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>>
>>
>> ----
>> Ted Leung                 Open Source Applications Foundation (OSAF)
>> PGP Fingerprint: 1003 7870 251F FA71 A59A  CEE3 BEBA 2B87 F5FC 4B42
>>
>
>
----
Ted Leung                 Open Source Applications Foundation (OSAF)
PGP Fingerprint: 1003 7870 251F FA71 A59A  CEE3 BEBA 2B87 F5FC 4B42