Re: Possible conditional construct for discussion

I thought about the thing that I was suggesting with parameters/variables
and realize that Richard's suggestion of writing my data into an XML
document and using it down-stream was correct.

Back to the syntax discussion...

I know that this is coming from left field and that I am not an implementor,
however please consider the following as my suggestion toward a bit of
the overall syntax. Notice that the steps no longer declare their 'type';
instead, I have made step a wrapper for an <p:xslt> or <p:xinclude> or
whatever components we make public. I am imagining that such elements
definitions would include subordinate elements for an appropriate number of
<input>, <output> and <param> elements, plus whatever other elements
might be appropriate to the specific component.

I imagine that components would prescribe the names to be used for
their input and output interfaces, for example in cases where a
component has multiple inputs or outputs with distinct roles.

<p:flow>
    <input name="source" src="file:stdin" />
    <output name="result" src="#inc.result"/>

    <choose>
       <input src="#source"/>
       <output name="cond.result"/>

       <when test="/*/@version = 1">
         <pipe>
           <step name="ss">
         <p:xslt>
             <input name="stylesheet" src="http://example.org/foo.xsl"/>
             <input name="source" src="#source"/>
             <param name="p" value="xyz"/>
             <param name="x" value="..." />
         </p:xslt>
           </step>
         </pipe>
       </when>
    </choose>

    <pipe name="inc">
       <step name="inc">
         <p:xinclude>
           <input name="include" src="#cond.result"/>
           <output name="result"/>
          </p:xinclude>
       </step>
    </pipe>

</flow>

I also imagine the possibility of an equivalent to a UNIX 'here' document, 
where
I can for example write

         <input name="boilerplate">
                 <P>Here is the XML document that I want to process</P>
         </input>

I will be gone to Europe on holiday between July 24 and July 10.

Ciao,

Murray