“This page intentionally left blank” after \part

Question

I sometimes use the following snippet to add a note to empty pages saying that they were intentionally left blank --- I'm not 100% sure where exactly it's from, but similar snippets can be found in various questions and answers, e. g. in How do I make pages which were “intentionally left blank”?:

\makeatletter
\def\cleardoublepage{\clearpage\if@twoside \ifodd\c@page\else
\mbox{}
\vspace*{\fill}
\begin{center}
This page intentionally left blank.
\end{center}
\vspace{\fill}
\thispagestyle{empty}
\newpage
\if@twocolumn\mbox{}\newpage\fi
\fi\fi}
\makeatother

It turns out that when using the book document class, empty pages inserted by \part do not carry this notice, so I'd like to share what I did to add the same notice to those, in the hopes that others may find it helpful.

Answer 1

The solution that worked for me was to redefine \@endpart (which is used internally by \part) in an analogous manner by replacing the \null it contains with the relevant code from the above snippet:

\makeatletter
\def\@endpart{\vfil\newpage\if@twoside \if@openright
\mbox{}
\vspace*{\fill}
\begin{center}
This page intentionally left blank.
\end{center}
\vspace{\fill}
\thispagestyle{empty}
\newpage\fi\fi
\if@tempswa\twocolumn\fi}
\makeatother

Answer 2

If you use the memoir class (a superset of book, report and article) then this will do it for you.

% partpageprob.tex  SE 586270
\documentclass{memoir}

\begin{document}
\nopartblankpage  % no blank page after a \part
\part{A PART}
 % go to a special page after \part, putting text on the skipped page
\movetooddpage[\thispagestyle{empty}%
  \vfil \begin{center}This page intentionally left blank\end{center}\vfil]
Some text
\chapter{A chapter}
\end{document}

You might find memoirs methods of moving to another page useful in general.