[Tex/LaTex] Run a macro before the start of each frame/slide

beamer

I have a macro that I want to run just before every new beamer frame. I could just a define myframe environment that runs the macro then starts a standard frame, but I'd rather do it differently if I can.

Beamer has neat \AtBeginSection functionality, but am I right in thinking there's no such analogue like \AtBeginFrame…

And would the situation be different if I actually wanted to do something before setting each slide? [Edit: I asked this last part as a separate question]

Best Answer

Use the patching facilities of etoolbox to patch \frame to do what you want.

Since \frame is parameterless, it'd seem like you want to do

\preto\frame{\foo}

This will cause \foo to happen before the frame.

If you want things to happen after all of the argument processing, it's significantly more complex because it appears that beamer follows lots of different paths. (I sort of gave up after \beamer@@@@frame which then sets \beamer@howtotreatframe in a bunch of different ways depending on some conditions.)

Here's a simple example:

\documentclass{beamer}
\usepackage{etoolbox}
\preto\frame{\typeout{Starting new frame.}}

\begin{document}
\begin{frame}
asdf
\end{frame}
\begin{frame}
asdf
\end{frame}
\end{document}
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