Change the space between footnote line and main text only locally

Question

From this answer, one knows that the vertical space between the footnote line and main text can be accessed via \skip\footins. But the examples in that answer all change this value globally. Is there some way to change this value only locally at one place? (A possible solution might be to change its value and then change it back, but I don't know how to restore the original value.)

The motivation of this question is the note I'm writing contains a lot of diagrams and page breaking can be a tricky issue -- on those pages with footnotes, using just \enlargethispage doesn't look very satisfying sometimes, and it would be nice to be able to reduce the vertical space between footnote line and main text at these places.

Answer 1

If you want to "enlarge" a page by reducing the footnote skip, you must be sure that the page contains footnotes in the first place.

Assuming this is the case, you can extend the standard output routine so that it resets \skip\footins to the normal value after each output. This allows you to temporarily give it a different value.

\documentclass{article}
\newtoks\o \o=\output
\output={\the\o \global\setlength{\skip\footins}{2pc}}
\usepackage{lipsum}
\begin{document}
\setlength{\skip\footins}{.2pc}
a\footnote{test}
\lipsum
a\footnote{test}
\lipsum
\end{document}