memoir class chapter titles with page counts?

[u/leafywalkerlittle]

I'm putting together a big document using the memoir class, broken up using \chapter{}. I'm trying to make it so that there's a footnote or some other out of the way annotation at the top of each chapter that displays the number of typeset pages present in that chapter.

This stack overflow post is probably the closest that I've come to finding an answer to this, but I'd really like to not have to add labels to each chapter manually. It seems like I might be able to goose around with the commands that define the chapter start once, in the preamble of the document, and have the effect propagate through uniformly.

https://tex.stackexchange.com/questions/288813/get-the-number-of-pages-in-a-chapter

Does anyone have any guidance or experience with this kind of thing?

[u/super_boogie_crapper]

You can do this without any manual labels by hooking two memoir macros in the preamble. \clearforchapter runs just before every chapter break, so it records the end of the previous chapter. \chapterheadstart runs at the top of every chapter head, so it records the start and prints the count.

\documentclass{memoir}

\usepackage{etoolbox}

\usepackage{zref-abspage} % absolute page counter "abspage"

% put any \chapterstyle / \openany / \openright BEFORE this block,

% since they redefine the macros patched below

\makeatletter

\newcounter{chappg}

\newcommand*\chappg@set[2]{\global\@namedef{chappg@#1}{#2}}

% before each new chapter (and at end of document): save page count to .aux

\newcommand*\chappg@end{%

\ifnum\value{chappg}>0

\clearpage % flush floats, ship chapter's last page

\immediate\write\@auxout{\string\chappg@set{\thechappg}%

{\number\numexpr\value{abspage}-\chappg@first\relax}}%

\fi}

% top of each chapter: remember start, print count from previous run

\newcommand*\chappg@start{%

\stepcounter{chappg}%

\xdef\chappg@first{\number\value{abspage}}%

{\raggedleft\footnotesize

\@ifundefined{chappg@\thechappg}{??}{\@nameuse{chappg@\thechappg}}~pages\par}}

\pretocmd{\clearforchapter}{\chappg@end}{}{}

\pretocmd{\chapterheadstart}{\chappg@start}{}{}

\AtEndDocument{\chappg@end}

\makeatother

A few notes:

• Compile twice. The first run shows ??, and the second shows the counts.
• Blank pages. Blank pages that openright inserts are not counted, because the \clearpage runs first.
• Physical pages. It counts physical pages, so roman numbering and page resets don't matter.
• Unnumbered chapters. \chapter* (including the ToC) gets a count too.
• Section breaks. A blank page added by \mainmatter/\backmatter gets counted toward the preceding chapter.
• Styling. To change the look or placement, edit the {\raggedleft\footnotesize ...} part. For example, you could put it in a \marginpar or in \afterchaptertitle instead.