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Re: xparse and hyperref: Token not allowed in a PDF string (PDFDocEncoding)

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Wed, 15 Jun 2011 14:14:44 +0100

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 On 14/06/2011 23:12, Heiko Oberdiek wrote: > Yes. \NewDocumentCommand defines the macro using e-TeX's \protected. > The result of \show\fooa: > | \fooa=\protected macro: > | ->FooA. > > \pdfstringdef uses \edef to expand the string, \protected > prevents this and the unexpandable macro is then filtered out: > | Package hyperref Warning: Token not allowed in a PDF string (PDFDocEncoding): > | (hyperref) removing \fooa' on input line 9. > >> Would it be possible to make >> \NewDocumentCommand macros work with hyperref bookmarks? > > No, even worse, you cannot provide a bookmark string > (\texorpdfstring) inside the definition, because it will not > be expanded and \texorpdfstring is not seen. > > >> I'd prefer >> using \NewDocumentCommand macros because of the mandatory argument of >> \DeclareExpandableDocumentCommand macros which I don't need in my context. > > I don't see that mandatory arguments matter here. > But probably you are refering to "1.7 Fully-expandable document commands": > | * The function must have at least one mandatory argument, and in > | particular the last argument must be one of the mandatory types > | (l, m or u). > > The section 1.7 contains advice against \DeclareExpandableDocumentCommand: > | do not use these functions! > One translation is: Good bye bookmarks. > > Of course there are macros, whose definition text makes it > difficult for bookmarks anyway (assignments, ...). But > the expandable macros are excluded using \DeclareDocumentCommand. > > Workarounds: > * \pdfstringdefDisableCommands can be used, but > an expandable macro needs to be added for each \protected > macro that might appear in bookmarks. Then the redefinition > takes place for each bookmark string conversion, not very > efficient. > * Expandable wrapper command that expands to the bookmark string > if inside bookmarks and calls the unexpandable macro otherwise. > * LuaTeX would add access to node lists, thus the > bookmark string could be set in a \hbox and the node list > examined and converted to a text string. Some cases are > probably quite easy, other cases are very difficult and > would cry for OCR methods. Clearly, dealing with bookmarks is something that will need to be addressed in the longer term in a more systematic way: it is not the intention to say 'Good bye bookmarks'! To me, it seems that:  - only some document commands need to work inside bookmarks, although    it takes a human to decide which ones.  - the definition for use within bookmarks needs to be carefully worked    out, so again automation is out.  - definitions for expandable contexts will in general be different from    non-expandable ones. There are a number of ways we could handle this. One way would be to have a \DeclareBookmarkableCommand (or similar) macro, which would work in the form    \DeclareBookmarkableCommand\foo{m}      {Standard code}      {Bookmark code} and then to define \foo as Heiko suggests   \def\foo{\texorpdfstring{\InternalFoo}{Bookmark Code}} although I'm not sure what happens in other expandable contexts (I assume anything other than a bookmark context uses branch 1). A second alternative would be to go with Frank's idea of separating out interface and implementation   \DeclareDocumentCommandInterface   \DeclareDocumentCommandImplementation and to provide a way to switch implementations. I think I prefer the first approach, but in general expandable versus non-expandable document commands are still a problem, as are variations in implementation. So we may need to think a bit more widely about this. -- Joseph Wright`