Re: [Adobe-source-devel] visual eve editor

[Sean P. <sp...@ad...>]

On Dec 15, 2006, at 9:11 PM, Ralph Thomas wrote:

>  slider( value: 50, name: "a slider" );
>
> Whereas with XML, all attributes look like strings:
>
>  <slider value="50" name="a slider"/>
>
> Unless you make the syntax more verbose:
>
>  <slider>
>    <attribute type="int" name="value">50</attribute>
>    <attribute type="string" name="name">a slider</attribute>
>  </slider>

There are a couple of options here and nearly any choice has an  
example in common use - one is to have a two level parser - this is  
the approach of the XPath syntax when used in XSL. Here you would  
have something like:

<slider value='50' name='(a slider)'/>

Here we borrow the PDF syntax (xpath doesn't have a very rich type  
system) as a sub-syntax. The problem with this is if you allow  
complex expressions then you need a fairly complete sub-parser:

button(items: ["OK", "Cancel"]); // simplified properties

<button name='[(OK) (Cancel)]'>

Getting to full expressions gets even more complicated - the approach  
used by XFA is to imbed full expression in the sub-syntax:

<Calc>Quantity * UnitPrice</Calc>

Borrowing from XFA (which is in some respects similar to Adam) may  
not be a bad idea.

If we avoid the sub-syntax then following the lead of MXML is likely  
a way to go:

<mx:Array>
   <mx:String >OK</mx:String>
   <mx:String>Cancel</mx:String>
</mx:Array>

A common request is for the embedding of Eve descriptions in MXML  
(has a lot to do with where I work :-) ). Larry sent me a paper at  
one point on extending MXML which is related.

There is also the option of simply imbedding CEL in XML - this would  
allow for structural manipulation using XSL (a big advantage of an  
XML syntax) and we'd get away with our existing CEL parser. This  
would require escaping which is also done with XPath in XSL.

Here we might have something like:

<slider value='50' name='&quot;a slider&quot;'/>

This would likely be the approach for xstrs - so we could have the  
very verbose:

slider(value: 50, name: "<xstr id='slider'>a slider</xstr>"); // CEL  
syntax

<slider value='50' name='&quot;&lt;xstr id=&apos;slider&apos;&gt;a  
slider&lt;/xstr&gt;'>

Oh what fun!

I think what is needed more than an XML expert is a customer - so  
far, anytime someone has asked for an XML syntax (and this happens  
often) there isn't any use case that warrants it. The question comes  
up enough though that I get tired of answering it and one solution  
might be to just pick _any_ XML syntax. The one major exception being  
the answer "I want to use Adam/Eve with Flex" but that requires more  
than just a move to an XML syntax - but I am interested in this  
project if I can find the bandwidth (or volunteers).

At some point, I want to tackle style sheets for Eve - For example,  
be able to have styles for the OK-Cancel cluster being on the top- 
right (Photoshop style) - bottom-right (Mac style) or bottom  
distributed (Windows style) - this kind of structural manipulation is  
a natural use case for XSL but I haven't had time to explore. Oddly  
though, I don't have others asking for this capability.

Sean