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[closed] Re: Should defaulted ports be named?

From: Norman Walsh <ndw@nwalsh.com>
Date: Fri, 25 Jan 2008 10:31:46 -0500
To: public-xml-processing-model-comments@w3.org
Message-ID: <m2ir1hncpp.fsf@nwalsh.com>
Overtaken by events, I believe.

/ Richard Tobin <richard@inf.ed.ac.uk> was heard to say:
| The defaulted output port of a subpipeline is given the name "result".
| And the defaulted input and output ports of a pipeline (if we keep them)
| are given the names "source" and "result".
|
| Since the purpose of these is to simplify the very basic case of
| straight-line pipelines, wouldn't it be better for them to have
| unusable names such as "!result"?  As it is, you can have explicit
| references to a port which is not declared.  This is not only bad
| for readability, but makes it more complicated to analyse.  Consider:
|
|   <p:group name="g0">
|
|     <p:group name="g1">
|       <p:identity>
|          <p:input><p:pipe step="g2" port="result"/></p:input>
|       </p:identity>
|       ...
|     </p:group>
|
|     <p:group name="g2">
|       ...
|     </p:group>
|
|   <p:group>
|
| To determine that g0 doesn't get a defaulted output, you have to
| discover that g2's defaulted output is read in g1.  But when you
| process g1, you may not have determined that g2 has a defaulted output
| yet.  This is not impossible to solve, but it's another unexpected
| constraint on the order you have to analyse the program in.
|
| -- Richard

                                        Be seeing you,
                                          norm

-- 
Norman Walsh <ndw@nwalsh.com> | We have fewer friends than we imagine,
http://nwalsh.com/            | but more than we know.--Hugo Von
                              | Hofmannsthal

Received on Friday, 25 January 2008 15:32:20 GMT

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