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

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6
votes
3answers
388 views

Expandable string substitution

I am trying to define a macro \formatstr{\mystring}{(string empty)}{the string is: #1} which expands to (string empty) when \mystring is empty (as judged, e.g. by etoolbox's \csdefempty) and ...
4
votes
2answers
260 views

Define command either with or without \csname

I'm trying to do the same as this one, but with \def, \gdef or \xdef instead. Very quick summary of the other question: I wanted to print the command (not the contents of the command) regardless of ...
7
votes
1answer
308 views

Print name of command, defined by \csname

First off: I do not understand \expandafter and \noexpand completely which is probably the main problem. I have found a question that explains what it does, but still I cannot seem to make it work. I ...
12
votes
3answers
315 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 ...
27
votes
1answer
404 views

Why six \noexpand in a row?

Trying to understand TeX's rules for parsing dimensions, I came up with the following weird behaviour: \dimen0=1\noexpand\noexpand\noexpand\noexpand\noexpand\empty pt is valid, but ...
10
votes
3answers
261 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 ...
10
votes
2answers
511 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{} ...
1
vote
0answers
169 views

how to create a fully-expandable environment [closed]

I know DeclareDocumentCommand from the package xparse. I am wondering if there is a version for environment ? I could also imagine a trick based on : declare the environment with ...
8
votes
1answer
147 views

On pitfalls of robust commands

These days, I’m more and more defining robust commands, e.g., using \newrobustcmd (etoolbox package) or \NewDocumentCommand (xparse package). Robust commands seem advantageous to me in many respects ...
6
votes
3answers
181 views

How to “demux” several aspects from a `\foreach` variable with `\ifstrequal`?

How can I "demux" several features from a mode specification given in a \foreach? I would like to use a \foreach to draw several nodes in a TikZ picture. The loop will specify a mode for each ...
6
votes
1answer
153 views

How can I inhibit expansion through several layers of \edef?

I'm using a macro I've defined based on some suggestions here to automate the creation of tables. For example something like \newcommand{\clearrows}{\let\matrixcontent\empty} ...
6
votes
2answers
235 views

How to redefine commands and environments, and make them acceptable for `\write`

My general problem is the following. I want to "convert" many .tex files into some other format (xml-like). I don't want to modify the tex files, I can only build a documentclass. The texfiles are ...
7
votes
1answer
708 views

A \typeout (or expandable command) that can expand once - or with variable levels of expansion?

Consider the following MWE: \documentclass[12pt]{article} \begin{document} \def\aaa{something} \typeout{=1==\aaa==} \typeout{=1==\meaning\aaa==} \typeout{} \def\bbb{else \aaa, else} ...
9
votes
2answers
356 views

Expandable author names from biblatex?

Knowing that \printnames command in biblatex is not expandable as it is protected, and I cannot otherwise do much about it; I thought about going through biblatex.sty and reconstructing \printnames ...
15
votes
3answers
797 views

Why does \dimexpr swallow \relax?

Following the comments at Doing maths with distance values in LaTeX source code: +1 for teaching me that \dimexpr can optionally swallow a \relax. Yesterday I tried to use \relax as a delimiter ...
22
votes
4answers
1k views

On testing two fully expanded character strings for equality

I know three macros that test two fully expanded character strings for equality: \ifthenelse{\equal{<op1>}{<op2>}}{<true>}{<false>} (ifthen package) ...
7
votes
1answer
270 views

Defining inside an \edef

The following throws an "Undefined control sequence" error: \edef\testa{\edef\testb{foobar}\testb} when it gets to expanding \testb. This problem is also mentioned in "TEX by Topic" 12.6.2. But no ...
12
votes
1answer
276 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 ...
9
votes
6answers
729 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}} ...
6
votes
2answers
509 views

Expanding (edef) a lipsum command?

Just trying to debug some stuff, and I thought about 'expanding' a \lipsum[1-2] statement using \edef into a new command (that would contain the "raw" text); strangely I cannot get it to work; this ...
2
votes
2answers
277 views

An expandable 'character scanning' command?

Please consider the following MWE, for a "character scanning" command "\looper" which utilizes \@tfor: \documentclass{minimal} \usepackage{trace} \makeatletter \newcommand\looper[1]{% % ...
15
votes
1answer
457 views

How do I ‘expand’ a control sequence `\let` to a character?

Consider the following: \let\1=X \edef\2{\1} \show\1 \show\2 The result is > \1=the letter X. > \2=macro: ->\1. Is it possible to ‘expand’ the meaning of \1 so that \2 contains just ...
11
votes
4answers
348 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 ...
5
votes
2answers
397 views

On unprotecting (expanding) \protected macros (or, “the space after command name”)

I quite often come into a situation, where I need to obtain some text produced by a package macro as a string, like in say: Expanding (edef) a lipsum command? How do I "unprotect" an ...
6
votes
3answers
127 views

Expansion issue: How Check if options passed to an environment were used

I have an environment with portions of the content that being conditionally typeset based on options passed to the environment. The content of this environment is predefined elsewhere so depending on ...
7
votes
3answers
427 views

\expandafter parameters that are not commands

I'm using a custom command to format all tables in a document. Some tables share properties other than style, such as column definitions and headers, which is why this answer inspired me to even more ...
4
votes
3answers
192 views

Using a macro evaluating to a set of xkeyval arguments as argument to another command

I am trying to code a macro that adds xkeyval arguments contained in a macro to a list of default xkeyval arguments. The following minimal example explains better what I want to do. ...
4
votes
2answers
323 views

expand macro in single byte encoded code

In this minimal (not) working example, I try to use single-byte latin10-encoded source file, and expand a command-macro containing a character with \catcode254: % -*- mode: latex; unibyte: t; ...
5
votes
2answers
169 views

Latex3 input/output and expansion of macros

I have a package that formats a course outline and have a macro that reads a formatted user file and turns it into a section. \documentclass{article} \usepackage{xparse} \ExplSyntaxOn \tl_new:N ...
5
votes
1answer
314 views

\unexpanded fails with undefined LaTeX symbols?

I'm actually not sure if the title of this post is correct. However, what is happening is that the following MWE \documentclass{article} \begin{document} \unexpanded{$\undefsym{x}$} \end{document} ...
8
votes
1answer
503 views

'Undefined control sequence' error when defining a color through a macro

I'm trying to color a cell using its data value. However, when I try to compute some value (using the content of the cell) then the definition of the color color!\somemacro in the \cellcolor does not ...
5
votes
1answer
182 views

Print the counter given as an argument

I have a counterA and a counterB. I want to define a command \PrintCounter, which gets either A or B as argument, and then prints the value of the corresponding counter. I wrote the following code: ...
13
votes
3answers
1k views

Expandable version of \InputIfFileExists or \IfFileExists

From this question: Cannot use \toprule when doing \input inside tabular -- why? I know that everything inside the tabular environment should better be expandable. The MWE below suggests that ...
2
votes
1answer
222 views

How to add \hline to macro expansion?

I want to add one \hline to the macro expansion of this code, that is minimally modified version of David Carlisle's answer to Generating LaTeX tabular code during compilation. Compiling this with ...
8
votes
2answers
479 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 ...
8
votes
2answers
167 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: ...
25
votes
4answers
561 views

Why isn't a command defined by \newcommand with an optional argument expandable?

In trying to fix a problem with a nested macro repeatedly calling itself, I tried expanding the inner call before passing it as an argument to the outer one. This failed miserably because the macro ...
8
votes
2answers
2k views

Cannot use \toprule when doing \input inside tabular — why?

Using \input inside a tabular environment does not seem to work in all cases, but I don't see why. The MWE below gives the following error message: ! Misplaced \noalign. \toprule ->\noalign ...
3
votes
1answer
252 views

LaTeX3: expansion of argument to function

I would like to define functions which extract the PDF object number from a PDF object reference, such as 12 from 12 0 R. I defined two versions of such a function, a low level one and a high level ...
4
votes
1answer
86 views

How to use a counter in a \bookmark dest name within \BookmarkAtEnd?

I'm trying to do something similar as in this question. I would like to use the value of a counter in the name of a \hypertarget and in addition, I want to be able to refer to this name in a ...
7
votes
2answers
321 views

Convert string to file name and use in \href

I have a bunch of individual .tex files and want to be able to click on a link in one PDF file and have the appropriate PDF file open. These are small files, so don't really need to index into them, ...
12
votes
1answer
287 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
2answers
541 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 ...
11
votes
2answers
453 views

\expandafter within a \begingroup … \endgroup [duplicate]

Possible Duplicate: What does \begingroup\expandafter…\endgroup do? In many of Heiko Oberdiek's packages one sees this type of construction: ...
6
votes
1answer
163 views

How to extend the \romannumeral-based \fullyexpand to handle empty/all-space arguments?

In Expandable full expansion of tokens that preserves catcodes, Joseph Wright presents the following code: \long\def\fullyexpand#1{% \csname donothing\fullyexpandauxi{#1}{}% } ...
9
votes
1answer
698 views

Highlighting line ranges in a lstlisting: partial solution, but expansion issues

In my quest for a better solution for How to change appearance of a particular line when using \lstincludelisting, I came across the linebackground= option Martin Scharrer added to the listings ...
7
votes
5answers
2k views

\includegraphics: a command in the optional argument

I want to pass some arguments to \includegraphics via a command, but I can't get it working as I would expect. My M(n)WE: \documentclass{article} \usepackage{graphicx} \begin{document} ...
7
votes
1answer
226 views

Why do some arguments in a macro need to be preceded by \noexpand?

I keep on studying the use of nested tikzpicture environments (sorry) and I discover the next problem. I'm not sure but it sounds like a problem with "fragile" commands. Perhaps, the problem is the ...
6
votes
1answer
382 views

How to expand values stored in a token defined by newtoks

In this project, the directory structure and file names are based on three parameters, with there being one exception to both. Directory Path: \GetTexFilePath{}{}{} The directory path is based on ...
15
votes
4answers
576 views

Detokenizing without extra spaces?

I have a need to pass through potentially arbitrary characters untouched and found this macro: \def\test#1{\expandafter\zap@space\detokenize{#1} \@empty} The problem is that \detokenize inserts ...