[OpenAjaxIDE] Multiselect properties - must have datatype of array

Jon Ferraiolo jferrai at us.ibm.com
Thu Aug 7 08:49:33 PDT 2008


There are lots of ways to address this requirement. Here are two that come
to mind:

Option 1: Do nothing special in the metadata spec to address Bertrand's
performance concern. Microsoft's property manager logic would recognize
that it is working with its own widgets somehow and provide a more
efficient code path that uses bitfields instead of arrays. (Bertrand would
have to say whether this option is feasible for MS's products)

Option 2: Add a new 'bitfield' type for the 'format' attribute, so you
would have <options datatype="Number" format="bitfield">. We explain that
if format="bitfield", then the 'value' attributes on the <option> element
must be unique powers of 2, such as <option value="1">, <option value="2">,
<option value="4">, etc, and require that tools save a Number (more
specifically, an integer) into the property storage system.

There are other options. I'm willing to go along with most everything so
long as we make a reasonable attempt to avoid unnecessary vendor-specific
features.

Jon




                                                                           
             Wayne                                                         
             Vicknair/Austin/I                                             
             BM                                                         To 
                                       Bertrand Le Roy                     
             08/07/2008 07:56          <Bertrand.Le.Roy at microsoft.com>     
             AM                                                         cc 
                                       "ide at openajax.org"                  
                                       <ide at openajax.org>,                 
                                       ide-bounces at openajax.org, Jon       
                                       Ferraiolo/Menlo Park/IBM at IBMUS      
                                                                   Subject 
                                       Re: [OpenAjaxIDE] Multiselect       
                                       properties - must have datatype of  
                                       array(Document link: Jon Ferraiolo) 
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           



I believe that the <options> and <option> element combination do indeed
express a constrained, multiple-value parameter.  HTML DOM and Dojo's
dijit.form.MultiSelect both happen to implement that concept with an,
admittedly inefficient, array return value. That implementation does not
diminish the expressiveness of the <options> construct. An implementation
could choose to iterate over the array values converting them to numbers
and bitwise  or-ing them together.

Cheers,
Wayne
Wayne E. Vicknair
Consulting Product Design Professional
IBM SWG Emerging Internet Technologies
Office: 512.838.0707 Email: waynev at us.ibm.com



                                                                           
             Bertrand Le Roy                                               
             <Bertrand.Le.Roy@                                             
             microsoft.com>                                             To 
             Sent by:                  Jon Ferraiolo/Menlo Park/IBM at IBMUS  
             ide-bounces at opena                                          cc 
             jax.org                   "ide at openajax.org"                  
                                       <ide at openajax.org>                  
                                                                   Subject 
             08/06/08 07:50 PM         Re: [OpenAjaxIDE] Multiselect       
                                       properties - must have datatype of  
                                       array                               
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




Same thing that happens in C. Never been a problem as you rarely have the
many flag values. Storing a list of countries or states would be more
efficiently stored in more elaborate data structures. The use we have of
flags is typically stuff like read/write/readwrite or left, right, top,
bottom and combinations. You get the idea. Bit structures are way more
efficient for this type of situation.
Sure, HTML options are different but I’m not sure I see your point.
Anyway, that’s the design we have in our APIs and it would be nice if it
was possible to express it.

From: Jon Ferraiolo [mailto:jferrai at us.ibm.com]
Sent:: Wednesday, August 06, 2008 5:32 PM
To: Bertrand Le Roy
Cc: ide at openajax.org
Subject: RE: [OpenAjaxIDE] Multiselect properties - must have datatype of
array



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.


Inactive hide details for Bertrand Le Roy <Bertrand.Le.Roy at microsoft.com>
Bertrand Le Roy <Bertrand.Le.Roy at microsoft.com>


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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