Show title in margin first time a work is cited

Question

The core of my question is how to define a macro that does something different the first time it is called with a given argument. And further, have the ability to reset that so that that first time behaviour can be restored.

I want to use this to cause citations to show the cited work's title the first time they are used, in the margin.

This is what I have come up with, using etoolbox flags.

\documentclass[]{article}
\usepackage{etoolbox}
\usepackage[style=authoryear, backend=biber]{biblatex}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%Arguments: namespace,key,if first-action, if-not-first action
\newcommand{\iffirstuse}[4]{%
    \global\providetoggle{#1#2}%
    \global\nottoggle{#1#2}{#3}{#4}%
    \global\toggletrue{#1#2}%
}

\let\oldcite\cite
\def\citenamespace{citeA}
\renewcommand{\cite}[1]{%
    \iffirstuse{\citenamespace}{#1}%
    {%
        \oldcite{#1}%
        \marginpar{\citetitle{#1}}%
    }{%
    \oldcite{#1}%
    }%
}

\newcommand{\resetcitescount}{%
    \xdef\citenamespace{{\citenamespace}A}
}

%%%%%%%%%%%%%%%%%%%%%%


\begin{filecontents}{\jobname.bib}
    @book{Labov1972,
        Address = {Philadelphia},
        Author = {William Labov},
        Publisher = {University of Pennsylvania Press},
        Title = {Sociolinguistic Patterns},
        Year = {1972}}

    @book{Chomsky1957,
        Address = {The Hague},
        Author = {Noam Chomsky},
        Publisher = {Mouton},
        Title = {Syntactic Structures},
        Year = {1957}}
\end{filecontents}

\addbibresource{\jobname.bib}


\begin{document}
It was said that there were patterns (\cite{Labov1972}.)\\
\cite{Labov1972} speaks of patterns in language based on society.\\
This can be contrasted with the earlier work of \cite{Chomsky1957}.\\
\cite{Labov1972} is newer than \cite{Chomsky1957}\\
With all that said\\
and all that done\\
\resetcitescount{} 
Do not forget \cite{Chomsky1957}

\end{document}

This works, but I am not sure if it is the best way.

Further I don't know how well it would scale to all the complexities of the different cite commands in biblatex, like \parencite{refone,reftwo,refthree}.

Is there a smarter way to do this?

Answer 1

The test \ifciteseen checks if the current entry was seen/cited before. It must be enabled with the citetracker option.

In the example below I patched the cite bibmacro with xpatch to include the title in the margin if needed.

\documentclass[]{article}
\usepackage{etoolbox}
\usepackage[style=authoryear, backend=biber, citetracker=true]{biblatex}

\usepackage{xpatch}

\makeatletter
\xapptobibmacro{cite}{%
  \ifciteseen
    {}
    {\scbx@savepunctstate
     \marginpar{%
       \scbx@resetpunctstate
       \printfield[citetitle]{labeltitle}}%
     \scbx@restorepunctstate}%
}{}{}

\newcommand*{\scbx@savepunctstate}{%
  \let\scbx@saved@unitpunct\blx@unitpunct
  \let\scbx@saved@tgl@unit\etb@tgl@blx@unit
  \let\scbx@saved@tgl@block\etb@tgl@blx@block
  \let\scbx@saved@tgl@insert\etb@tgl@blx@insert
  \let\scbx@saved@tgl@lastins\etb@tgl@blx@lastins
  \let\scbx@saved@tgl@keepunit\etb@tgl@blx@keepunit
}

\newcommand*{\scbx@restorepunctstate}{%
  \global\let\blx@unitpunct\scbx@saved@unitpunct
  \global\let\etb@tgl@blx@unit\scbx@saved@tgl@unit
  \global\let\etb@tgl@blx@block\scbx@saved@tgl@block
  \global\let\etb@tgl@blx@insert\scbx@saved@tgl@insert
  \global\let\etb@tgl@blx@lastins\scbx@saved@tgl@lastins
  \global\let\etb@tgl@blx@keepunit\scbx@saved@tgl@keepunit
}

\newcommand*{\scbx@resetpunctstate}{%
  \let\blx@unitpunct\@empty
  \global\togglefalse{blx@block}%
  \global\togglefalse{blx@unit}%
  \global\togglefalse{blx@insert}%
  \global\togglefalse{blx@lastins}%
  \global\togglefalse{blx@keepunit}%
}
\makeatletter


\begin{filecontents}{\jobname.bib}
@book{Labov1972,
  address   = {Philadelphia},
  author    = {William Labov},
  publisher = {University of Pennsylvania Press},
  title     = {Sociolinguistic Patterns},
  year      = {1972},
}

@book{Chomsky1957,
  address   = {The Hague},
  author    = {Noam Chomsky},
  publisher = {Mouton},
  title     = {Syntactic Structures},
  year      = {1957},
}
\end{filecontents}

\addbibresource{\jobname.bib}


\begin{document}
It was said that there were patterns \parencite{Labov1972,Chomsky1957}.

\cite{Labov1972} speaks of patterns in language based on society.

This can be contrasted with the earlier work of \cite{Chomsky1957}.

\cite{Labov1972} is newer than \cite{Chomsky1957}

With all that said
and all that done

\citereset
Do not forget \cite{Chomsky1957}
\end{document}

\scbx@savepunctstate and friends are just to avoid unwanted side-effects of two different tracking levels for punctuation, see Sidecite only once per page.