{expansion} is about expanding tokens, including the manipulation of expansion order and the suppressing of expansion.

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13
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1answer
142 views

\( \) don't work with TOC?

If i write this line of code \subsection{Ranger \( n \) boules distinguables dans \( M \) boîtes} I obtain an error over the second \) (./Probabilité.toc ./Probabilité.toc:8: LaTeX Error: Bad ...
13
votes
2answers
1k views

Allow underscore in PGFPlots tick labels read from table

I'm trying to use the text data from a table column as the tick labels in a plot. The text data contains underscores, which makes LaTeX throw a Missing $ inserted error. I'd usually get around this by ...
12
votes
4answers
413 views

Create a capitalized macro token using \csname

Two things I understand and one thing I don't: I often use \csname to create user-defined tokens. For instance, the following code uses \expandafter to expand everything between \csname and ...
12
votes
2answers
886 views

Minimal \protected@edef example

I recently came across \protected@edef in the/a LaTeX2e source. Can anyone give me a minimal or simple example, where I need this? I know this has to do with fragile commands/robustness, but I am ...
12
votes
2answers
642 views

Macro to do nothing via a \def

I have encountered another expansion issue and have narrowed it down to this simple test case of a macro that does nothing, well at least it tries to do nothing, but is not all that successful. If I ...
12
votes
3answers
332 views

Expansion of first token in a tabular cell

Background I currently do some work on the collcell package which collects the content of a tabular/array cell and provides it to a user defined macro, e.g. using ...
12
votes
1answer
318 views

Why does \expandafter not expand the full { } group?

I thought I had understood the principle of expansion ... but apparently not! \def\a{AAA} \def\b{BBB} \expandafter\detokenize\expandafter{\a\b} I thought that the 2 \expandafter would store ...
12
votes
1answer
294 views

Text being output when none should be

I am confused as to why the MWE below produces any black text. As the code is below, the output is: However, if you comment out the \IfStrEq line then it works fine and the black text goes away? ...
12
votes
1answer
2k views

renewcommand in a newcommand

I have a command \putansline{1}{2} that inserts 1 line of dots and prints the total score as [2]. I want to define a new command that if issued, will redefine this command so that it prints only the ...
12
votes
1answer
359 views

How to expand a macro used in the range of a foreach loop?

Motivating Example: Suppose that I want to draw the following tree: root / \ / \ / \ A B C D This is easy enough to do by explicitly drawing the two subtrees as children of ...
11
votes
4answers
196 views

Partially expanding a command

My \john command is defined like so: \def\john{\DontExpandMe} I would now like to repeatedly change its definition, to keep adding some extra stuff on the front. \foreach\i in {ape,bat,cow,dog} { ...
11
votes
3answers
175 views

How to pass a macro as the argument to \selectlanguage

The following mwe throws the error You haven't defined the language lang yet. \documentclass{article} \usepackage[american]{babel} \newcommand{\lang}{american} \selectlanguage{\lang} \begin{document} ...
11
votes
3answers
286 views

Expandable 'character scanning' command that preserves spaces

David Carlisle recently offered a clean and rather elegant TeX solution to a question about expandable 'character scanning' commands. Unfortunately, David's solution does not preserve spaces in the ...
11
votes
2answers
306 views

Define and set length in one command

Sorry this might be a very simple question, I am trying to cleanup a style file, and would like to write a command that basically runs the following code: ...
11
votes
2answers
749 views

Tricks to make macros expandable

Expandable macros are useful (I find working in the lion's mouth super cool). But they are difficult to write. Can more experienced users give hints that help achieve expandability? For example, we ...
11
votes
1answer
626 views

How to do \scantokens inside \edef without triggering “Runaway definition”

I'm trying to find a way to use the e-TeX \scantokens command inside [the equivalent of] an \edef (well, actually an \xdef, but presumably this does not make any real difference since that's just the ...
11
votes
4answers
644 views

What's the best/right way to test an argument to a macro?

This is essentially asking how to do a case switch in LaTeX. I want to define a macro so that if the argument passed is one thing, then something happens, and if not then something else happens. I ...
11
votes
1answer
87 views

\toks register expansion issue - or is it?

I am trying to assemble a table that occurs multiple times throughout a document. It always consists of some fixed columns, followed by a set of columns that appear in one table but are not needed in ...
11
votes
1answer
180 views

expandable unit conversion

I'm writing a package to assist typesetting documents for some special Pen & Paper Fantasy RPG. In this fantasy setting, there are three types of coins: gold, silver and copper pieces, which ...
10
votes
5answers
483 views

How to create a “delay expansion” environment?

I don't want to use the following \begingroup \edef\next{\endgroup \noexpand\const{Xp}{\X(tp)} \noexpand\const{Yp}{\Y(tp)} \noexpand\const{Xf}{\X(tf)} \noexpand\const{Yf}{\Y(tf)} ...
10
votes
4answers
266 views

why can't \the be expanded?

\documentclass{article} \begin{document} \tracingmacros=2 \newlength{\len} \setlength{\len}{1cm} we want to write out \verb$\len$ in cm \the\len { oops, answer in pt} \setlength{\len}{0.0352\len} ...
10
votes
3answers
191 views

\expandafter and counters not playing nicely

My google-fu has finally failed me... I'm trying to write a package that will allow you say \addauthor{name, email} several times and have the title page properly formatted. Here is a minimal example ...
10
votes
2answers
311 views

How do I pass an expanded optional argument using expl3/xparse?

I have a command defined using xparse syntax: \DeclareDocumentCommand \foo { O{} m } {} Inside some other command (say, \bar), I want to call this command. The calling command (\bar) has to ...
10
votes
2answers
640 views

How to use \noexpand in an \edef?

Continuing with my struggle to deal with expansion issues, I am stuck on how to use an \edef properly. The code below with the switches set as: %\def\ApplyColorToTitle{} %\def\UseMathrmInTitle{} ...
10
votes
2answers
161 views

Preserving (and Controlling) Expandedness

In most cases, by the time output gets to your screen, arguments are fully expanded and my question is moot. But sometimes (verbatim being a common example), one wishes to operate on arguments with ...
10
votes
2answers
193 views

Execute non-expandable code inside a tabular environment

As there is no Expandable version of \InputIfFileExists or \IfFileExists, the question arises whether it is possible to execute non-expandable code in a tabular environment after all: File main.tex: ...
10
votes
2answers
543 views

Concurrently interleaving execution of Lua and TeX in LuaTeX

The usual way to interleave Lua and TeX in generating documents is by invoking Lua from Tex through the \directlua facility and generate Tex from Lua using tex.print(). For example, consider the ...
10
votes
4answers
378 views

Changing the behavior of $$ but not of $

I am trying to set things up so that occurrences of $$ are replaced by \] if in math mode, \[ otherwise. My strategy is to make $ active and have it behave differently depending on whether the ...
10
votes
1answer
2k views

Add space after LaTeX command

I'd like to call a command from LaTeX, which looks like this: bash -c "\myCommand -Tpdf #2.dot > #2.pdf" \myCommand is replaced by string variable, however the space after is also removed so I ...
10
votes
3answers
670 views

Censor text spanning multiple lines

I'd like to censor or hide some text while replacing it with the appropriate amount of white-space. The replacement text cannot be searchable. The text to be hidden usually exists in the LR mode. The ...
10
votes
1answer
127 views

Environment with delayed expansion

I'm trying to define an environment test that stores its contents unexpanded in a macro \testcontents. For example, the code \newcommand{\cmd}{bad} \begin{test} \cmd \end{test} ...
10
votes
2answers
123 views

Expandably change letter case and use inside \csname, without a package

I want to change the letter-case of a single character argument, and use that changed letter inside a \csname. And I want to do it without an additional package. For example, I want to pass a macro ...
10
votes
1answer
127 views

Macro parameter delimited by more than one delimiter

TeX user can simply create the macro with a parameter delimited by an arbitrary sequence of tokens. For example \def\macro #1delimiter{...#1...} Is it possible to create a macro with a parameter ...
10
votes
2answers
221 views

Save counter value inside command?

I'm trying to automatically generate commands based on the value of a counter: \documentclass{article} \newcounter{count} \newcommand\generator[1]% {% \stepcounter{count}% ...
10
votes
1answer
119 views

Expandable, very specific keyval processing

I am having a hard time trying to come up with an fully expandable keyval parsing macro which deals only with specific keys/values. I wouldn't even attempt this in full generality, that's way beyond ...
10
votes
1answer
56 views

Reading (input) a file whose name is created with a label

I don't want to get into the details of why I want to do this, but I would like to: create a new counter called filenumber; create a file whose filename is \jobname\thefilenumber.txt and write to ...
10
votes
1answer
447 views

Extract the logically first slide in a Beamer overlay specification?

When writing Beamer slides for a talk, I find that I often want to have some text (usually math) visible on a group of slides and be alerted on only the first slide in the group. For example, I can ...
9
votes
5answers
323 views

Parse dotted string, extracting last part

I want a macro that will separate a string like "1.2.3" into two parts: the part until the last dot (call that the context) and the last number. This seems a pretty basic application of a helper ...
9
votes
6answers
864 views

Defining new commands inside a for loop

I would like to define a number of related commands by using the counter in a for-loop. For example, I want to define 26 commands like this: \newcommand{\calA}{{\cal A}} \newcommand{\calB}{{\cal B}} ...
9
votes
6answers
660 views

Is there a '\ReallyDontExpandUntilTheLastMinute' command?

There's a couple of things I want to be able to do that are quite similar and basically involve keeping back a macro expansion until the last minute. Possibly the simplest example is that I have a ...
9
votes
3answers
195 views

Command doing the same job as StrBefore but being expandable

I am looking for a command allowing me to get 3 as output if the input is 3.2. \StrBefore{3.2}{.} works fine for this purpose but is not expandable and I need to call it in another macro inside a ...
9
votes
2answers
93 views

How to expand \ifthenelse so that it can be used in \parshape?

How do I get the following MWE to work: \documentclass{article} \usepackage{xifthen} \usepackage{lipsum} \newboolean{bar} \setboolean{bar}{true} \def\foo{\parshape = 2 ...
9
votes
4answers
165 views

Apply command to list of elements separated by \and

I am trying to build a command similar to the \author command. It takes one argument with is actually a list of arguments separated by \and. The command needs to apply another command like \underline ...
9
votes
2answers
641 views

Force the expansion of a macro parameter without \edef or \xdef

Two days I am looking for a solution but I have no more idea. This is my problem. I'm trying to create a macro to automatically define new other macros to write references in a document. I want to ...
9
votes
3answers
152 views

Problem with ^^<HEX>

I have small problem with ^^<HEX>. If I have a <HEX> part of the ^^<HEX> in the macro \def\attemp{<HEX>}, I cannot write ^^<HEX> as ^^\attempt or ...
9
votes
2answers
337 views

How does this answer work?

Harald Hanche-Olsen posted some interesting code in answer to this question. Could someone explain how it works? I understand (I think) the futurelet and the expansions. I don't understand: Where ...
9
votes
3answers
605 views

Problem with nested \noexpand and \edef

I have a LaTeX problem and want to explain it with the following code snippet: \documentclass{article} \begin{document} \def\myline{A} \edef\myline{\myline \noexpand\bf B} \edef\myline{\myline ...
9
votes
2answers
276 views

How can I encode the current document as a QR code with pst-barcode?

\documentclass{article} \usepackage{pst-barcode} \begin{document} \begin{pspicture} \psbarcode{\input{\jobname.tex}}{}{qrcode} \end{pspicture} \end{document} I tried placing \expandafters before ...
9
votes
3answers
203 views

Completely expandable loop macro that also works in tabular

Since I normally use tikz in my documents, I mostly use the \foreach \x in \list loop to repeat things. However, this famously fails in tabular environments and also everywhere where things must be ...
9
votes
2answers
215 views

Still having difficulty with use of `\expandafter`

Firstly, my apologies for any previous confusion, I've separated out various questions onto distinct pages. This problem came up in the context of trying to split a decimal number. Good solutions to ...