Scoping \raggedbottom to a single page

Question

How does one define a single page to be \raggedbottom? Or, for completion's sake, \flushbottom?

Background

In a comment to a related answer, Ben Lerner provided the following snippet of code to declare a single page to be \raggedbottom:

\def\oneraggedpage{\raggedbottom\afterpage{\flushbottom}}

When I tried this, it did not work as expected: instead of making a single page \raggedbottom it made the entire document. Besides, even if this is made to work) this way of doing things assumes that the default state (into which the document needs to return after the page is shipped out) is \flushbottom, which may or may not be the case (cf. \ensuremath).

So the question is, what is the best way to scope the effects of \raggedbottom (or some such) to a single page?

(Apologies for no MWE, but it's difficult to come up with one in this case)

Sample case

If it helps to think about how this could be useful, think of writing a paper in which the references go in an additional page at the end. By default, the last page can be ragged even without \raggedbottom. But if the last page will have the references, the "final page" of the document itself would be the page before the references.

Maybe in this case (the actual case that motivated me) the changes can be integrated into the bibliography's environment?

Answer 1

\afterpage groups its argument, and as \flushbuttom doesn't set its values globally they are lost. You need a "global" variant of \flushbottom:

\documentclass{article}

\usepackage{afterpage}
\usepackage{lipsum}
\begin{document}
\flushbottom
\lipsum[1-2]
\pagebreak
\raggedbottom\lipsum[1-2]
\makeatletter
\afterpage{\global\let\@textbottom\relax \global\let\@texttop\relax}
\pagebreak\lipsum[1-2]
\pagebreak abc


\end{document}

Answer 2

Updated \global added before \let in \afterpage as explained in Ulrike Fischer's answer. Without that the code below does not work as intended - \raggedbottom is applied to two consecutive pages not one. Thanks to StevenB.Segletes for pointing this out.

Here is a version capturing the current setting, assuming the bottom alignment is achieved purely by adjusting \@textbottom and \@texttop. This is true in standard LaTeX, and in the memoir class. It does not quite capture memoirs \sloppybottom though.

\documentclass{article}

\usepackage{afterpage}
\usepackage{lipsum}

\makeatletter
\newcommand{\oneraggedpage}{\let\mytextbottom\@textbottom
  \let\mytexttop\@texttop
  \raggedbottom
  \afterpage{%
  \global\let\@textbottom\mytextbottom
  \global\let\@texttop\mytexttop}}

\begin{document}
\flushbottom
%\raggedbottom
\lipsum[1-6]

\vspace{1ex plus 30ex}
\vrule height 10cm
\vspace{1ex plus 30ex}

\oneraggedpage
\lipsum[7]

\vspace{1ex plus 30ex}
\vrule height 10cm
\vspace{1ex plus 30ex}

\lipsum[8-20]

\end{document}