Adding page number to the even page right after \part

Question

Friends, I've never used \part{} before, so bear with me. =)

Consider the following code:

\documentclass[twoside]{book}
\usepackage{lipsum}

\begin{document}

\pagestyle{empty}
\begin{titlepage}
My title page.
\end{titlepage}

\cleardoublepage
\pagestyle{plain}

\frontmatter
\tableofcontents
\clearpage
\mainmatter

\part{Hello World}
\chapter{Test one}
\lipsum[1]
\section{My section one}
\lipsum[1]

\part{Goodbye World}
\chapter{Test two}    
\lipsum[1]
\section{My section two}
\lipsum[1]

\end{document}

I'd like to have page numbers in the even pages right after the Part x titles. It would be pages 6 and 10 of my example.

I could redefine the empty pagestyle to act as plain, but I didn't want to do that. In fact, I tried that - and it works - but I also need empty pagestyles in my original document.

I suppose \part is like a book division, so it should look like another "cover" (what would explain why there's no number in the hm... back of the page). In my particular case, I need that number to be in there.

Does anybody have an idea?

Answer 1

But you can redefine the empty page style to be plain and do it locally using \begingroup, \endgroup; for example (only the page following part one will receive number):

\documentclass[twoside]{book}
\usepackage{lipsum}

\begin{document}

\pagestyle{empty}

\begin{titlepage}
My title page.
\end{titlepage}

\cleardoublepage

\pagestyle{plain}

\frontmatter

\tableofcontents

\clearpage

\mainmatter

\begingroup
\makeatletter
\let\ps@empty\ps@plain
\makeatother

\part{Hello World}

\endgroup\chapter{Test one}
\lipsum[1]

\section{My section one}
\lipsum[1]

\part{Goodbye World}

\chapter{Test two}    
\lipsum[1]

\section{My section two}
\lipsum[1]

\end{document}

Remark:

As Frank Mittelbach says in his comment, introducing groupings that go across the LaTeX concepts can be "dangerous". In this particular case, there's no harm, but in case of chapter and section one might see side effects already (the indentation is no longer suppressed for example).

Answer 2

Here is a patch with etoolbox for numbered pages following part pages:

\usepackage{etoolbox}
\makeatletter
\patchcmd{\@endpart}{empty}{plain}
\makeatother

The macro \@endpart causes the empty page style, which is replaced by plain by this patch.

Answer 3

You could also redefine the macro \@endpart from the file book.cls, which looks like:

\def\@endpart{\vfil\newpage
          \if@twoside
           \if@openright
            \null
            \thispagestyle{empty}% the instruction I believe you want to remove
            \newpage
           \fi
          \fi
          \if@tempswa
            \twocolumn
          \fi}

If I understand your explanation correctly, all you require is to suppress the instruction \thispagestyle{empty}. This may be achieved by (i) commenting out this instruction in the file book.cls and saving the class file to a new file, say, "mybook.cls" -- note that it is very much against the LPPL to save the change under the existing file name -- or (ii) by providing a modified definition for this macro in the preamble of your document, sandwiched between \makeatletter and \makeatother instructions:

\makeatletter
\def\@endpart{\vfil\newpage
          \if@twoside
           \if@openright
            \null
            %%\thispagestyle{empty}% this instruction is now commented out
            \newpage
           \fi
          \fi
          \if@tempswa
            \twocolumn
          \fi}
\makeatother

See also @StefanKottwitz's answer for a way to achieve this objective using the tools of the etoolbox package.

Answer 4

In memoir, this is very simple (that's why I love memoir). In the preamble:

\aliaspagestyle{afterpart}{plain}  % (Instead of plain, whatever you want)