[closed] Re: Determining whether a pipeline has a (defaulted) output

I think we've nailed this one. Twice. :-)

/ Richard Tobin <richard@inf.ed.ac.uk> was heard to say:
| A pipeline with no output declarations has an output if its last step
| does.  Its last step may be a call to another pipeline, so we have to
| determine whether that has an output.  Now consider:
|
| <p:pipeline-library xmlns:p="http://www.w3.org/ns/xproc" 
|                     xmlns:e="http://example.org" namespace="http://example.org">
| <p:pipeline name="pipe1">
|   <e:pipe2/>
| </p:pipeline>
|
| <p:pipeline name="pipe2">
|   <p:choose>
|     <p:when test="foo">
|       <p:identity/>
|     </p:when>
|     <p:otherwise>
|       <e:pipe1/>
|     </p:otherwise>
|   </p:choose>
| </p:pipeline>
|
| </p:pipeline-library>
|
| (Does anyone have an implementation that can handle it?)
|
| We can deduce that both pipe1 and pipe2 have an output, because
| otherwise the choose would have inconsistent outputs, but that seems
| a rather undesirable way to proceed.
|
| -- Richard

                                        Be seeing you,
                                          norm

-- 
Norman Walsh <ndw@nwalsh.com> | The things we have most longed for do
http://nwalsh.com/            | not happen; or if they do, it is never
                              | at the time nor under the circumstances
                              | when they could have made us
                              | happiest.--La Bruyère