[OpenAjaxIDE] Multiselect properties - must have datatype of array

Jon Ferraiolo jferrai at us.ibm.com
Wed Aug 6 17:32:28 PDT 2008


What happens if you are doing multi-select with more than (4bytes) 32
alternatives (e.g., # states in US) or more than (8bytes) 64 alternatives
(e.g., # countries in the world)?

HTML's OPTION element doesn't require the use of bit flags (i.e., values
which are powers of 2), and that's what our <option> element will be mapped
into for a large number of cases.





Options are for enums, right? If so, that is completely different from our
usage. Multiple value enums (or flags) have integer values (like in C) and
are combined through the  | or operator. Testing for a specific value is
done with the & and operator.
So for example, you’d have:
<property name="FavoriteAnimals">
__<options multiple="true">
____<option value="1"><label locid="animal_panda">Panda</label></option>
____<option value="2"><label locid="animal_tiger">Tiger</label></option>
____<option value="4"><label locid="animal_cat">House cat</label></option>
____<option value="8"><label locid="animal_dog">Man's best
friend</label></option>
__</options>
</property>

And if the user picks Tiger and House Cat, that gives 6.

From: ide-bounces at openajax.org [mailto:ide-bounces at openajax.org] On Behalf
Of Jon Ferraiolo
Sent: Wednesday, August 06, 2008 10:14 AM
To: ide at openajax.org
Subject: [OpenAjaxIDE] Multiselect properties - must have datatype of array



Aaron Reed of IBM is implementing the <property><options multiple="true">
feature in the open source reference implementation and the question can up
about how to represent the multiple choices when the property value is
persisted into the property storage area. Here is an example:

<property name="FavoriteAnimals">
__<options multiple="true">
____<option value="panda"><label
locid="animal_panda">Panda</label></option>
____<option value="tiger"><label
locid="animal_tiger">Tiger</label></option>
____<option value="cat"><label locid="animal_cat">House
cat</label></option>
____<option value="dog"><label locid="animal_dog">Man's best
friend</label></option>
__</options>
</property>

Let's suppose the user picked "Tiger" and "House cat".

Given that we are focused on JavaScript, our proposal is that the natural
way to store a multi-select option would be as a JavaScript array. In this
case, the array would be ["tiger","cat"].

Does this make sense to people?

If so, then should we change the spec to say that if a <property> uses
<options> with multiple="true", then the <property> element must have
datatype="[]".

A follow on question is whether we should require an array of Strings, or
is it OK to have an array of anything, such as Number? Is the array could
contain things other than String, then implementations would need to a
string-to-whatever conversion at some point (e.g., string-to-number). I
would thing that array-of-Strings is the way to go.

Jon

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