expl3 conflicts with tikz

Question

When I use expl3 with tikz errors are raised (pdflatex). My complete code is

\documentclass{article}
\usepackage{tikz}
\ExplSyntaxOn
\begin{document}
\begin{tikzpicture}
\draw(0,0)--(3,3);
\end{tikzpicture}
\end{document}

You can see the effect here. I notice that using xelatex the code in the link compiles correctly. Nevertheless it sometimes still functions badly.

What is the method to have them work better together?

Please cite the error you get. Just visiting the link you provided compiles without error on overleaf for me — daleif, Dec 25 '22 at 06:21
See Workaround how to use expl3 functionality in tikz - TeX - LaTeX Stack Exchange and linked questions. — user202729, Dec 25 '22 at 06:39
That having said in this particular example just move \ExplSyntaxOn after \begin{document} can fix. — user202729, Dec 25 '22 at 06:40
There is no reason to do \ExplSyntaxOn just before \begin{document} and several for not doing it. — egreg, Dec 25 '22 at 08:58
remove explsyntaxon it is doing nothing useful in that position. if you did have some expl3 code in the preamble follow it by \ExplSyntaxOff — David Carlisle, Dec 25 '22 at 09:50

score 5 · Accepted Answer · answered Dec 25 '22 at 11:03

Doing \begin{document} under the scope of \ExplSyntaxOn is a very bad idea, sorry.

Several packages delay loading configuration files at begin document and inputting a file under the \ExplSyntaxOn regime is, to say the least, risky: spaces and endlines are ignored and if a file does

\mycountera=100
\ifnum\mycounterb=\mycountera 10\else 0\fi

(made up code to show one of the possible issues) you'd end with \mycountera holding the value 10010 or 1000, depending on the current value of \mycounterb. The given code is valid and would set \mycountera to 100 when spaces aren't ignored, then print 10 or 0. But when spaces are ignored, the \ifnum is expanded prior to TeX having determined the value passed to \mycountera.

Think to \ExplSyntaxOn as bringing an aircraft to the hangar for installation of new equipment. You want to end the installation before pulling the aircraft on the runway for take-off, don't you?

When you're under \ExplSyntaxOn regime, never do typesetting. Well, sometimes

\ExplSyntaxOn<expl3 code>\ExplSyntaxOff

might be appealing inside document. Avoid it and define prior to \begin{document} a user level command doing the business: install the equipment first, then take-off.

David's answer to Checking whether an item of a string is space is a case: his usage of \ExplSyntaxOn inside document was just by way of example, but not aimed to be what you'd do in a real document.

expl3 conflicts with tikz

1 Answers1