Re: Annoyances with parameter input ports

Toman_Vojtech@emc.com writes:
> Sorry, I don't understand. I just wanted to make it sufficient to
> specify p:with-param without an explicit binding for  parameter input
> ports. I didn't want to change any of the present behavior with respect
> to overwriting parameter values by using different orders of
> p:with-param, parameter bindings, etc.

So we'd be trading one default behavior for another. Consider this
pipeline:

  <p:pipeline name="main" ...>
    <p:xslt>
      <p:input port="stylesheet">
        <p:document href="http://.../docbook.xsl"/>
      </p:input>
      <p:with-param name="root-dir" select="'./html'"/>
    </p:xslt>
  </p:pipeline>

At the moment, if I pass additional parameters on the command line,
they all get passed to the XSLT step and they allow the caller to
overide my default for the 'root-dir' parameter.

If I want to make my 'root-dir' parameter the only acceptable value,
then I can do so explicitly:

  <p:pipeline name="main" ...>
    <p:xslt>
      <p:input port="stylesheet">
        <p:document href="http://.../docbook.xsl"/>
      </p:input>
      <p:input port="parameters">
        <p:pipe step="main" port="parameters"/>
      <p:with-param name="root-dir" select="'./html'"/>
    </p:xslt>
  </p:pipeline>

And if I want to make my 'root-dir' parameter the *only* parameter, I
can do that explicitly:

  <p:pipeline name="main" ...>
    <p:xslt>
      <p:input port="stylesheet">
        <p:document href="http://.../docbook.xsl"/>
      </p:input>
      <p:input port="parameters">
        <p:empty/>
      <p:with-param name="root-dir" select="'./html'"/>
    </p:xslt>
  </p:pipeline>

Under your proposal, if I understand it, my original pipeline:

  <p:pipeline name="main" ...>
    <p:xslt>
      <p:input port="stylesheet">
        <p:document href="http://.../docbook.xsl"/>
      </p:input>
      <p:with-param name="root-dir" select="'./html'"/>
    </p:xslt>
  </p:pipeline>

would have the effect of making 'root-dir' the *only* parameter. But
if I wanted to allow other parameters, I could do so explicitly, as
above, and make the 'root-dir' parameter the fixed value or the
default value.

On the whole, I think the status quo behavior is more likely to be
what users expect and want. But in either case, some semantics can
only be achieved explicitly, and *all* semantics can be achieve
explicitly, so I'm not (yet, at least) convinced that it's worth
changing the status quo.

Getting parameters right was *a lot* of work and took *a long time*.
I'm a little gun shy about touching them unless the benefits are
overwhelming. But maybe that's just me.

                                        Be seeing you,
                                          norm

-- 
Norman Walsh <ndw@nwalsh.com> | Why in our youth does the life we still
http://nwalsh.com/            | have before us look so immeasurably
                              | long? Because we have to find room for
                              | the boundless hopes with which we cram
                              | it.-- Schopenhauer