Renewcommand footnoterule only in a single page

Question

Is it possible to use \renewcommand\footnoterule{} for a single page only ?

In other words, taken into account that separators are already set in pages 1-3, can I remove the footnote separator on my fourth page and set it again in my fifth page ?

Actually, I found some codes using the bigfoot/manyfoot packages, but they did not really help me to get what I want...

Answer 1

The footnote rule is typeset when the page number is already known. You can modify the definition of \footnoterule to do nothing when the page number is 4, taking advantage to the fact that the rule actually takes up no vertical space on the page.

\documentclass{article}
\usepackage[paperheight=4cm,paperwidth=3in,margin=1.3cm]{geometry}

\makeatletter
\renewcommand\footnoterule{
  \ifnum\c@page=4 \else
    \kern-3\p@
    \hrule \@width 2in \kern 2.6\p@ % the \hrule is .4pt high
  \fi
}
\makeatother

\begin{document}

a\footnote{a}\clearpage
b\footnote{b}\clearpage
c\footnote{c}\clearpage
d\footnote{d}\clearpage
e\footnote{e}

\end{document}

How to have a list of pages where not to use \footnoterule? Here's a way.

\documentclass{article}
\usepackage{xparse}

% just to get smaller pictures
\usepackage[paperheight=4cm,paperwidth=3in,margin=1.3cm]{geometry}

\ExplSyntaxOn

% keep the original \footnoterule
\cs_new_eq:NN \guillaume_footnoterule: \footnoterule
% redefine \footnoterule
\cs_set_protected:Npn \footnoterule
 {
  \bool_set_true:N \l_guillaume_footnoterule_bool
  \seq_map_function:NN \g_guillaume_footnoterule_pages_seq \guillaume_test:n
  \bool_if:NT \l_guillaume_footnoterule_bool { \guillaume_footnoterule: }
 }
\cs_new_protected:Nn \guillaume_test:n
 {
  \int_compare:nT { #1 = \value{page} }
   {
    \seq_map_break:n { \bool_set_false:N \l_guillaume_footnoterule_bool }
   }
 }
% save the list of pages where not to have a footnoterule
\seq_new:N \g_guillaume_footnoterule_pages_seq
\NewDocumentCommand{\nofootnoterule}{m}
 {
  \seq_gset_from_clist:Nn \g_guillaume_footnoterule_pages_seq { #1 }
 }
\ExplSyntaxOff

\nofootnoterule{1,3,4}

\begin{document}

a\footnote{a}\clearpage
b\footnote{b}\clearpage
c\footnote{c}\clearpage
d\footnote{d}\clearpage
e\footnote{e}

\end{document}

The command \nofootnoterule populates a sequence and at the moment when \footnoterule is called by the kernel, the current page number is checked against the sequence.