List of Unused \newbox, \newcount, \newdimen, \newskip, etc

Question

Want a appropriate command to list out unused Box, Counter, Dimension, Skip from the CLS/STY file.

Answer 1

Since the question appears to be about the resources taken up by register allocations it should be noted that despite the names \newbox, \newcount etc do not generate new box or count registers.

There are 256 or 32768 or 65536 registers of each type available (depending on the engine). These are available all the time whether or not you allocate anything.

\count600=42

sets count register 600 to 42 and doesn't need you to allocate 600 registers with \newcount.

\newcount\mycount

or

\newbox\mybox  

just declare \newcount or \newbox to be a number associated to the register (in the case of \newbox just using \chardef usually.)

So the only extra resource of having unused \newcount is like the resource of \let\myname\@empty of the space taken up to store the commandname itself, and its association to the register.

in etex and xetex there is the theoretical issue that the first 256 "classical" registers are stored more efficiently than the extended registers (which are stored as a sparse array) but on modern machines this is unlikely to make any observable difference, and isn't an issue in luatex at all, which stores the full set of 65536 registers in the same way.

If you always access the registers via non-expandable macros, those macros could be extended to log usage, but in general this is not possible, if you have a usage like

\newcount\mycount
...
\typeout{\the\mycount}

Then it is unlikely that you can log the usage of \mycount from within tex in any reliable way. It is of course easy just to search for \mycount in your source files in an editor or using sed or perl etc, so that is likely to be the most reliable method.

If your class files have lots of unused register allocations (or even lots of register allocations that are used) then there is something very strange in the code, very few classes have more than ten or so such allocations.

Answer 2

Here is an example of how to locate any unused \newbox. The MWE below defines three boxes:

\newbox{\MyBoxA}
\newbox{\MyBoxB}
\newbox{\MyBoxC}

but only box \MyBoxB is ever used, so the other two get reported as unused:

Notes:

• \usepackage{debugboxes} needs to be before any \newbox.

• If you comment out the \usepackage{debugboxes}, then things work as normal, but when that is included, you get the report of unused boxes.

• The filecontents package was used to package the test case and create the debugboxes.sty. It is not needed in you actual use case.

---

Code:

\begin{filecontents*}{debugboxes.sty}
\usepackage{pgffor}
\usepackage{etoolbox}
\usepackage{expl3}
%%% http://tex.stackexchange.com/questions/100542/how-to-extract-the-name-of-a-macro
\ExplSyntaxOn
    \newcommand{\CsToStr}[1]{\cs_to_str:N #1}
\ExplSyntaxOff
%% http://tex.stackexchange.com/questions/14393/how-keep-a-running-list-of-strings-and-then-process-them-one-at-a-time
\newcommand\SaveboxList{}
\makeatletter
\newcommand{\AddToSaveboxList}[1]{%
    \g@addto@macro\SaveboxList{#1,}%
}
\makeatother
\let\OldNewBox\newbox
\renewcommand{\newbox}[1]{%
    \AddToSaveboxList{\CsToStr{#1}}%
    \OldNewBox{#1}%
}%
\let\OldUsebox\usebox%
\renewcommand{\usebox}[1]{%
    \csgdef{SaveboxUsed \CsToStr{#1}}{}%
    \OldUsebox{#1}%
}%
\AtEndDocument{%
\bigskip
    \section{Unused saveboxes}%
    \foreach \x in \SaveboxList {%
        \ifcsdef{SaveboxUsed \x}{}{%
            \par\noindent\x
        }%
    }
}%
\end{filecontents*}
\documentclass{article}
\usepackage{debugboxes}% Comment this out if don't need the debugging,
\newbox{\MyBoxA}
\newbox{\MyBoxB}
\newbox{\MyBoxC}
\begin{document}
\savebox{\MyBoxB}{some content placed in box}
\usebox{\MyBoxB}
\end{document}