Re: Default binding of parameter input ports

Jeni Tennison <jeni@jenitennison.com> writes:
[...]
> Am I correct that:
>
> <p:declare-step>
>    <p:output port="result" />
>
>    <p:xslt>
>      <p:input port="source">...</p:input>
>      <p:input port="stylesheet">...</p:input>
>    </p:xslt>
> </p:declare-step>
>
> is invalid for the same reason? (With the possible fixes being to  
> explicitly indicate that the 'parameters' input port for <p:xslt> is  
> empty, or to create a primary parameter input port for the declared  
> step.)

Yes.

> [snip]
>>> What I am proposing is something like this:
>>>
>>> If there is a p:with-param for a parameter input port, that port gets
>>> *never* connected to the primary parameter input port of the owner
>>> pipeline automatically; if you want that, you can always use an  
>>> explicit
>>> binding. If there is no p:with-param for a parameter port, the port  
>>> gets
>>> connected to the primary parameter input port of the owner pipeline.
>>
>> I guess I could live with that, but it's much more of a coin toss to
>> me. Parameters are pretty confusing, I really don't know if making the
>> rules more complex helps or hurts with respect to users figuring out
>> what they need to do.
>
> FWIW, what I'd expect is, in:
>
> <p:pipeline>
>    <p:xslt>
>      <p:input port="source">...</p:input>
>      <p:input port="stylesheet">...</p:input>
>      <p:with-param name="foo" select="..." />
>    </p:xslt>
> </p:pipeline>
>
> for the parameters passed to the pipeline to get passed through to the  
> XSLT, with the $foo parameter always provided with the default value  
> that's specified on the <p:with-param>.

And that's what you'd get.

> And in:
>
> <p:declare-step>
>    <p:output port="result" />
>    <p:xslt>
>      <p:input port="source">...</p:input>
>      <p:input port="stylesheet">...</p:input>
>      <p:with-param name="foo" select="..." />
>    </p:xslt>
> </p:declare-step>
>
> for the XSLT to be passed only the $foo parameter and nothing else  
> because the step declaration has no primary parameter input port.
>
> In other words, I agree with Vojtech that the presence of the <p:with- 
> param> should mean that the lack of connection to the XSLT steps  
> primary parameter input port doesn't matter; but I don't agree with  
> him that the presence of the <p:with-param> should cancel out the  
> implicit connection between the primary parameter input port on the  
> step and the one from its container.

Although I didn't actually say it, this is what I had in mind when I
spoke of making the rules more complex. If we change the status quo,
then I think Jeni's proposed semantics are the right ones.

                                        Be seeing you,
                                          norm

-- 
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