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Re: Describing parameters

From: Jeni Tennison <jeni@jenitennison.com>
Date: Mon, 06 Nov 2006 14:56:37 +0000
Message-ID: <454F4D25.8050904@jenitennison.com>
To: public-xml-processing-model-wg@w3.org

Hi,

> Please review Section 4.2.4[1] of the alternate draft. (Nothing else
> has changed in that draft.)

Four things:

1. I think I'm right in saying that the only place where 
required="yes|no" is useful is on <p:parameter> directly within 
<p:pipeline>; in all other cases, parameters must be assigned a value. 
Given that assigning an actual value and assigning a default value are 
done in exactly the same ways, I think it would make sense to merge the 
identical parts of 4.2.4.1 and 4.2.4.2, something like:

  4.2.4 p:parameter Element
  4.2.4.1 Declaring Parameters
  4.2.4.2 Using Parameters
  4.2.4.3 Assigning Values to Parameters

2. In many cases, the value of a parameter will be derived from other 
parameters rather than from an input. Therefore, I think the various 
ways of identifying a context document (step+source, href, here 
document) should be optional rather than mandatory. In fact, I think I 
would prefer to mandate that one of 'select' or 'value' must be 
specified unless the <p:parameter> is a child of <p:pipeline> (and 
perhaps even mandate that one of 'select', 'value' or 'required' must be 
specified).

3. I'm really not sure about the value of 'here' documents when setting 
parameters. Why would you ever do:

   <p:parameter name="foo" select="/foo/@bar">
     <foo bar="baz" />
   </p:parameter>

when you could do:

   <p:parameter name="foo" value="baz" />

4. It strikes me that the functionality of <p:import-parameter> could be 
  supported using <p:parameter>. We could allow:

   <p:parameter name="*" />

within a step to mean "pass in all the in-scope parameters". Just as 
when declaring a parameter, if the name attribute doesn't hold a QName 
then you can't specify a value for the parameter.

5. I know that we made a decision to use "parameter" rather than "param" 
because we're not using abbreviations elsewhere, but I'm *so* used to 
writing "param" dammit! (As will be most XSLT users.) And "input" and 
"param" line up so nicely!

Cheers,

Jeni
-- 
Jeni Tennison
http://www.jenitennison.com
Received on Monday, 6 November 2006 15:18:38 GMT

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