Efficiently applying the same patch to several bibdrivers

Question

In this answer to a question about getting Biblatex to print the ISSN field for books, I suggest a solution which uses the \xpatchbibdriver command of the xpatch package:

\xpatchbibdriver{book}{%
  {\printfield{isbn}}
}{%
  {\printfield{issn}\newunit\newblock\printfield{isbn}}
}{}{}

A problem with my answer is that the patch needs to be applied separately for each book-like bibliography type (book, collection, proceedings, incollection, inproceedings, etc.).

Is there a nicer way to patch all the entries at once? I'm vaguely familiar with the \foreach command of the pgffor package, but the following naïve usage of it doesn't work, probably because it \i doesn't get expanded before getting passed to \xpatchbibdriver:

\usepackage{pgffor}
\foreach \i in {incollection,proceedings,book,inproceedings}{%
  \xpatchbibdriver{\i}{%
    {\printfield{isbn}}
  }{%
    {\printfield{issn}\newunit\newblock\printfield{isbn}}
  }{}{}
}

Is there a way I can force the expansion of \i? Do I need an \expandafter in here somewhere? (Alternatively, is there an even better way of doing what I'm doing without using pgffor and/or xpatch?)

A starter document would be nice, instead fragments of code ;-) — , Dec 08 '15 at 14:11

egreg · Accepted Answer · 2015-12-08T14:41:42.343

Since \xpatchbibdriver builds a command name with \csname...\endcsname, the \i macro is expanded

The patch is not performed because \foreach does its workings in a group and so the patch will disappear at the end. Use \@for:

\makeatletter
\@for\next:=incollection,proceedings,book,inproceedings\do{%
  \xpatchbibdriver{\next}
    {{\printfield{isbn}}}
    {{\printfield{issn}\newunit\newblock\printfield{isbn}}}
    {}{}%
}
\makeatother

With etoolbox features:

\renewcommand{\do}[1]{%
  \xpatchbibdriver{#1}
    {{\printfield{isbn}}}
    {{\printfield{issn}\newunit\newblock\printfield{isbn}}}
    {}{}%
}
\docsvlist{incollection,proceedings,book,inproceedings}

With xparse:

\documentclass{article}
\usepackage{biblatex}
\usepackage{xpatch,xparse}

\ExplSyntaxOn
\NewDocumentCommand{\massxpatchbibdriver}{mmmmm}
 {
  \clist_map_inline:nn { #1 }
   {
    \xpatchbibdriver{##1}{#2}{#3}{#4}{#5}
   }
 }
\ExplSyntaxOff

\massxpatchbibdriver{incollection,proceedings,book,inproceedings}
  {{\printfield{isbn}}}
  {{\printfield{issn}\newunit\newblock\printfield{isbn}}}
  {}{}

Thanks; I've used this to update the answer mentioned in my question. — Psychonaut, Dec 08 '15 at 14:41

Efficiently applying the same patch to several bibdrivers

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