#110 problem with length macros in `\deffootnote`

[Werner LEMBERG]

[v3.49.2]

Consider the following example code

\documentclass{scrartcl}

\newlength{\X}
\setlength{\X}{1em}

\deffootnote[1em]{1em}{1em}{%
  \textsuperscript{\thefootnotemark}~%
}

\def\Y{Bla bla bla bla bla bla bla bla}

\textheight 20ex
\textwidth  10em


\begin{document}

\framebox[1em]{X}

\framebox[\X]{X}

This is a test\footnote{\Y}.

\end{document}

As can be seen, it doesn't matter whether I use 1em or \X in the optional argument of the \framebox macro.

Image koma-script-length.png shows how this renders with pdflatex.

If I now replace the line

\deffootnote[1em]{1em}{1em}{%

with

\deffootnote[\X]{1em}{1em}{%

I get a different result, which is completely unexpected – the length is larger; see image koma-script-macro.png.

Maybe there is somewhere a line end in the code not being properly protected with %?

[Werner LEMBERG]

BTW, a similar effect happens if I replace 1em with \X in the first mandatory argument of \deffootnote.

[Markus Kohm]

When LaTeX runs \@makefntext the font size is already \footnotesize. Length \X is set to 1em in the font size of the active font at \setlength{\X}{1em} time not at usage of \X. So you would need to compare:

\documentclass{scrartcl}

\newlength{\X}
\setlength{\X}{1em}

\newcommand*{\Xmacro}{1em}

\deffootnote[1em]{1em}{1em}{%
  \textsuperscript{\thefootnotemark}~%
}

\def\Y{Bla bla bla bla bla bla bla bla}

\textheight 50ex
\textwidth  10em


\begin{document}

{\footnotesize
\framebox[1em]{X}

\framebox[\X]{X}\par}

This is a test\footnote{\Y{} using preamble 1em}.

\deffootnote[1em]{1em}{1em}{%
  \textsuperscript{\thefootnotemark}~%
}

This is a test\footnote{\Y{} using body 1em}.

\deffootnote[\X]{1em}{1em}{%
  \textsuperscript{\thefootnotemark}~%
}

This is a test\footnote{\Y{} using preamble length \the\X which is not
  \the\dimexpr 1em\relax}.

\deffootnote[\Xmacro]{1em}{1em}{%
  \textsuperscript{\thefootnotemark}~%
}

This is a test\footnote{\Y{} using preamble macro \the\dimexpr\Xmacro\relax
  which is \the\dimexpr 1em\relax}.

\end{document}

or:

\documentclass{scrartcl}

\newlength{\X}
\footnotesize
\setlength{\X}{1em}
\normalsize

\newcommand*{\Xmacro}{1em}

\deffootnote[1em]{1em}{1em}{%
  \textsuperscript{\thefootnotemark}~%
}

\def\Y{Bla bla bla bla bla bla bla bla}

\textheight 60ex
\textwidth  10em


\begin{document}

{\footnotesize
\framebox[1em]{X}

\framebox[\X]{X}\par}

This is a test\footnote{\Y{} using preamble 1em}.

\deffootnote[1em]{1em}{1em}{%
  \textsuperscript{\thefootnotemark}~%
}

This is a test\footnote{\Y{} using body 1em}.

\deffootnote[\X]{1em}{1em}{%
  \textsuperscript{\thefootnotemark}~%
}

This is a test\footnote{\Y{} using preamble length \the\X which is \the\dimexpr 1em\relax}.

\end{document}

[Markus Kohm]

Length are not macros.

Works as expected.

[Werner LEMBERG]

Ah, silly me, I forgot that 'em' is a relative size. Thanks for the explanation, and sorry for the noise.