Define \@ptsize rather than rolling our own \beamer@size

[jspitz]

This allows other packages (such as setspace) to determine the base font size.

AFAICS the \beamer@size macro is only used to input the proper *.clo file. This can be done with \@ptsize as well.

Furthermore, it makes \onehalfspacing or \doublespacing of setspace (who presuppose \@ptsize*) functional with beamer.

• See https://github.com/rf-latex/setspace/issues/5

[jspitz]

Note that with https://github.com/rf-latex/setspace/issues/5 being resolved, this PR is less urgent. Nonetheless it might be good to define \@ptsize

[samcarter]

I'm not sure if the general idea of changing the line spacing in beamer is such a good idea. There are many places in the convoluted beamer code, in which it assumes a somewhat normal linespacing. Changing the spacing can have funny effects, like an overflowing headline:

\documentclass{beamer}

\usetheme{Warsaw}
\usepackage{setspace}
\doublespacing

\begin{document}

\section{title} 
\begin{frame}
    abc
\end{frame} 
\section{title} 
\begin{frame}
    abc
\end{frame} 
\section{title} 
\begin{frame}
    abc
\end{frame} 
\section{title} 
\begin{frame}
    abc
\end{frame} 
\section{title} 
\begin{frame}
    abc
\end{frame}

\end{document}

[samcarter]

Closing as fixed in setspace https://github.com/rf-latex/setspace/commit/9c3eadc6a24f0bea2a046a872ef743507c6ea005

[jspitz]

FWIW I agree with the reservations of changing linespacing in a presentation. But people apparently do that and are irritated by the cryptic error (we got bug reports in LyX due to that).

Anyway the issue is resolved, and if you don't think setting \@ptsize in general is a good idea, I can live with that.