How to make biblatex treat the prenote like an author list?

Question

I am trying to customize a biblatex citation style (adapted from biblatex-juradiss). I have the problem that in my text I use many \cite commands which have two or more authors given in the prenote, and I want them formatted similarly to the editors of the publication that is referenced. So if I write

\cite[Smith, John and Johnson, Henry][23]{biblabel}

I would like the output to look like:

Smith / Johnson in: Editora / Editorb, other bibliographical data, p. 23.

where Editora and Editorb are the editor's surnames from the entry in my .bib file, and "other bibliographical data" stands for whatever biblatex would normally output after the editors. Biblatex does the editor list nicely, and I'd like the authors to look the same.

Please note that the slashes are not in italics, so I can't just give the additional author names inline with the slash in the prenote. Also, biblatex uses whitespace in the editor list which is somewhat narrower than usual.

Answer 1

The main problem is that name lists have to be parsed by Biber/BibTeX so they can be used properly. But the prenote and postnote field are local to the .tex file and are not passed to Biber for consumption.

So we either have to pass the prenote to Biber by means of writing to a temporary file, or we have to fake Biber's name parsing from within the document with biblatex/LaTeX itself.

The first method is can be implemented with limited extra work. The command \formatasname can be used anywhere to return a list of names as they would be written in a .bib file as biblatex would print them.

\formatasname writes the names it is given to a temporary .bib file and then cites them. In the process the names are parsed by Biber and are formatted just like other names.

Just be careful that you have no .bib file ending with -formatnames.bib in your folder. That file is automatically created by the code below and will be overwritten without warning.

\documentclass[british]{report}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}

\usepackage[style=authoryear, backend=biber]{biblatex}

\makeatletter
\DeclareCiteCommand{\nfblx@formatasname}
  {}
  {\printnames[labelname]{author}}
  {}
  {}

\def\nfblx@bibfile@name{\jobname -formatnames.bib}
\newwrite\nfblx@bibfile
\immediate\openout\nfblx@bibfile=\nfblx@bibfile@name
\newcounter{nfblx@name}
\setcounter{nfblx@name}{0}
\newcommand*{\formatasname}[1]{%
  \stepcounter{nfblx@name}%
  \edef\nfblx@tmp@cite{%
    \noexpand\nfblx@formatasname{nfblx@name@\the\value{nfblx@name}}%
  }%
  \nfblx@tmp@cite
  \immediate\write\nfblx@bibfile{%
    @misc{nfblx@name@\the\value{nfblx@name}, author = {\unexpanded{#1}}, %
          options = {dataonly=true},}%
  }%
}

\AtEndDocument{%
  \closeout\nfblx@bibfile}

\addbibresource{\nfblx@bibfile@name}
\makeatother

\addbibresource{biblatex-examples.bib}

\begin{document}
\cite[\formatasname{Humprey Appleby and Bernard Woolley} in:][13]{sigfridsson}
\printbibliography
\end{document}