- From: mozer <xmlizer@gmail.com>
- Date: Wed, 27 May 2009 07:40:21 +0200
- To: Norman Walsh <ndw@nwalsh.com>
- Cc: XProc Dev <xproc-dev@w3.org>
Norm, Are you suggesting that we eventually end up needing a construct to test if a variable is bounded ? Xmlizer On Wed, May 27, 2009 at 1:21 AM, Norman Walsh <ndw@nwalsh.com> wrote: > "Henry S. Thompson" <ht@inf.ed.ac.uk> writes: >> So, if I want to detect and handle specially the case where an >> optional option has not been specificed, how can I do so? > > You can't. And you know this bites harder than I realized. > > Consider the beginnings of a recursive directory listing step: > > <p:declare-step xmlns:p="http://www.w3.org/ns/xproc" > xmlns:c="http://www.w3.org/ns/xproc-step" > xmlns:pxp="http://exproc.org/proposed/steps" > type="pxp:recursive-directory-list"> > <p:output port="result"/> > <p:option name="path" required="true"/> > <p:option name="include-filter"/> > <p:option name="exclude-filter"/> > > <p:directory-list> > <p:with-option name="path" select="$path"> > <p:empty/> > </p:with-option> > <p:with-option name="include-filter" select="$include-filter"> > <p:empty/> > </p:with-option> > <p:with-option name="exclude-filter" select="$exclude-filter"> > <p:empty/> > </p:with-option> > </p:directory-list> > > </p:declare-step> > > Using four nested p:try/p:catch blocks to deal with the various permutations > of $include-filter and $exclude-filter being defined or undefined seems > pretty brutal. > > Be seeing you, > norm > > -- > Norman Walsh <ndw@nwalsh.com> | A man may by custom fortify himself > http://nwalsh.com/ | against pain, shame, and suchlike > | accidents; but as to death, we can > | experience it but once, and are all > | apprentices when we come to it.-- > | Montaigne >
Received on Wednesday, 27 May 2009 05:40:59 UTC