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

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9
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4answers
188 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
898 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
161 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
343 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
2answers
336 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
319 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
1answer
354 views

Expansion of macros and box contents

I don't understand the following behavior. Intro First, here is a simplified version of a macro I am using (which is itself a hacked version of a macro found in gloss.tex). If you have a string ...
9
votes
2answers
231 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 ...
9
votes
1answer
165 views

Is there a way of defining a command which is automatically converted to a no-op after its first execution?

Is there a way of defining a command that can be executed only once and is then redefined to be a no-op? Related: Is there a way of defining a command \nullifyifmoved{arg} that will normally act ...
9
votes
3answers
435 views

Implementing car and cdr in TeX

I've been trying to implement a macro that reads and transforms its argument into a different form...but I'm having quite a bit of trouble finding or creating even the most basic parsing tools. Case ...
9
votes
2answers
517 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 ...
9
votes
1answer
255 views

Expansion inside \AtBeginDocument

I'd like to expand a macro inside \AtBeginDocument, although I guess the concrete macro does not matter. \documentclass{article} \makeatletter \@for\x:=1,2,3\do{% ...
9
votes
1answer
2k views

Difference between \newcommand and \pgfmathsetmacro used in TikZ \coordinate

Consider the following code: \documentclass{article} \usepackage{tikz} \begin{document} \begin{tikzpicture} \newcommand{\MA}{4} \pgfmathsetmacro{\MB}{4}; \coordinate (V11) at (0,0); ...
9
votes
3answers
351 views

Write on a file and input it

I'm trying to redefine a \tableofcontents-like command. I proceed this way : the displayed elements are written to a file, and the file is input when I want the display. If I know the toc will be ...
9
votes
1answer
348 views

Using \typeout behaviour different with \newtoks vs. \def

I feel as I really should know this, but sadly I don't. Why is the output of \typeout{\the\myToken} not the same as having it printed in the PDF as \the\myToken. No problem with a \def, just with ...
9
votes
2answers
621 views

Expansion issue with \begingroup and \foreach

This question led to a new package: nowidow I'm trying to define a dynamic \begingroup command to get rid of widows: \usepackage{pgffor} \newcommand{\nowidow}[1][2]{% ...
9
votes
2answers
114 views

What is the preferred way of expanding twice in expl3?

expl3 includes the o, f, and x argument specifiers for one-level and the two kinds of full expansion, respectively, before passing the argument to the base function. What is the preferred way of ...
9
votes
1answer
2k views

Expansion in \numexpr…\relax versus \pdfstrcmp

The \numexpr...\relax construction in eTeX allows to evaluate numerical expressions, and it expands tokens fully as it goes. The \pdfstrcmp{...}{...} construction in pdfTeX lets us compare two lists ...
9
votes
2answers
331 views

Expansion problems with pgfkeys

I'm using pgfkeys, and a fairly adventurous syntax in which the values for some keys contain additional key/value pairs. (For instance, the value of the nodes key is a list of pairs, and the second ...
9
votes
1answer
287 views

“Flatten” macros prior to sharing LaTeX file

Is there a way/an existing tool to process a LaTeX source document such that for a given list of macro definitions (using \newcommand), calls to those macros are replaced by their expanded version? ...
9
votes
1answer
921 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 ...
8
votes
4answers
276 views

Does macros get applied to the source code before compilation?

I wonder if this is true. The latex compiler first run though the document, and search for all the macro declarations. the compiler then go though the document, apply each macro as a string ...
8
votes
3answers
557 views

Without any built-in looping macro, can we just use a recursive macro to get a-b-c-d-e?

Without any built-in looping macro, can we just use a recursive macro to get an output of a-b-c-d-e? \def\aaa #1{#1-\aaa} \aaa abcde % expected result : a-b-c-d-e \bye Edit: Probably the best way ...
8
votes
3answers
201 views

Are we inside an edef?

How would you test whether we are in an expansion only context (i.e., \edef, \xdef, \write,...) or not? The only ways I could think of leave things behind (but the full expansion of that extra stuff ...
8
votes
4answers
208 views

Problem with csname macro expansion

I want to dynamically define some macros that essentially create a list of \refs. I seem to be able to define these macros but then I am unable to print them. Here is my M(non)WE: ...
8
votes
2answers
638 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 ...
8
votes
2answers
132 views

How to use \edef to wrap an existing macro with @inmatherr?

I have a handful of existing macros that I want to wrap in some custom processing. Here's an example of the kind of thing I'm aiming to do: \makeatletter \let\olddag\textdagger ...
8
votes
3answers
276 views

Arguments possibly delimited by \bgroup and \egroup

I still don't see (and haven't thought about) pros and cons of making available the arguments as \foo{…} or \foo\bgroup …\egroup (or even unbalanced, \bgroup …} and {…\egroup). But I'm curious about ...
8
votes
3answers
251 views

Nested use of \ifcsname needs protection

I have a macro \command to ensure that the names of macros in my documentation are consistently formatted. Been work great, until I had an urge to procrastinate and had this brilliant idea that I can ...
8
votes
3answers
499 views

colortbl: new environments and how to apply \expandafter

This is a followup question from one asked by Andrew Howard. After some discussion, it became clear that colortbl has some issues with the names that can be used for a \newcolumntype. The result of ...
8
votes
5answers
207 views

How do I expand exactly once a macro which takes an argument

I thought I was finally understanding expansion, but then I wrote something along the following lines, and it has me a bit stumped. \documentclass{article} \usepackage{xcolor} \usepackage{etoolbox} ...
8
votes
2answers
291 views

How to control whether and when a macro gets expanded during another definition?

I wish to define a meta-command that, whenever invoked, will define an instance of another command; but this inner command must include a progressive number (somewhat similar to what happens with ...
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 ...
8
votes
2answers
559 views

How can I allow a command to be used without braces around its argument, when the argument has an argument?

I've defined a couple simple macros to make my life a little easier: \newcommand{\curl}[1]{\ensuremath{\nabla\times #1}} \renewcommand{\v}[1]{{\ensuremath{\vec{#1}}}} This way, in text mode I can ...
8
votes
1answer
107 views

Omitting arguments in macro expansion

Changing a simple TeX macro like \def\macro#1 #2{#1 #2} into \def\macro#1 #2{#1} alters the output of \macro Hello world surprisingly for me to Helloorld My expectation would have been to ...
8
votes
2answers
359 views

How to create an inline list via a macro

I want to create a macro that yields an inline lists. I can easily do this using enumerate* form the the enumitem package, but when I attempt to wrap this in a macro, I get: Extra }, or forgotten ...
8
votes
6answers
437 views

Is it possible to define a command that can be used where literal <comma-separated-list> is normally required?

I suspect I'm asking for magic, but I'll go ahead anyway. Suppose I have a command that accepts an arbitrary-sized list of comma-separated terms. One that we're all familiar with is \usepackage ...
8
votes
2answers
615 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 ...
8
votes
3answers
115 views

Appending active and expansion sensitive characters to a macro

This question comes up pretty often when people want to build tables with empty columns or similarly building up some active characters inside a macro hoping to expand them at the right time right ...
8
votes
2answers
252 views

Could someone explain the tokenization process that's leading the whitespace creeping in here?

Here's a MWE that creates spurious whitespace: \documentclass{article} \usepackage[T1]{fontenc} \usepackage{lmodern} \newcommand\aetest[2][\relax]{%% \def\aejunk{<#2>}%% \ifx\relax#1 ...
8
votes
1answer
126 views

How can I force expansion within this optional argument?

Oh look, a real question! In trying to actually complete something, I came across the following limitation of this lambda macro creator: it apparently does not work in the use case it was intended ...
8
votes
2answers
411 views

Expanding a sequence inside a TikZ path

I am trying to draw a simple path using TikZ, with a custom syntax to specify it. This works: \documentclass{article} \usepackage{tikz} \begin{document} \newcommand{\latticepath}[1]{ ...
8
votes
4answers
2k views

How to write a command to file

I am trying to write to a auxillary file using \newwrite\tempfile [...] \immediate\openout\tempfile=list.tex \immediate\write\tempfile{Text to write to file} \immediate\closeout\tempfile It works ...
8
votes
2answers
449 views

\g@addto@macro appending code using parameter

After a lot of trial and error, I haven't been able to solve the following problem: A simplified version: I want to use \g@addto@macro to add code to another macro wich will use a command of the ...
8
votes
1answer
117 views

Implement functionality equivalent to many thousand \savebox

I have a large (approx 600 pages) index of files, and for each file entry significant computation is required so that additional links can be added. The computation of these links takes quite a bit ...
8
votes
1answer
287 views

\href is not working inside \xdef

this is my first question here. I've already spent a substantial amount of time searching this before posting it here. This is my code: \documentclass[]{article} \usepackage{hyperref} ...
8
votes
2answers
516 views

Package xparse \SplitList last token

I need to create a macro to render lists with a variable number of arguments (1+), e.g. \mylist{1,2,3} should expand to $\tilde{1}$--$\tilde{2}$--$\tilde{3}$. I'm trying to use xparse and \SplitList, ...
8
votes
1answer
124 views

'Fake' variants in expl3

Suppose you have a function that operates on three tokens, \cs_new:Nn \@@_on_three:NNN { #1, #2, #3 } And you have a variable whose value is the three tokens: \tl_set:Nn \l@@_three_tl { foo } ...
8
votes
1answer
993 views

Problem with environment expansion and the Tikz external library.

I've created my own environment mytikz, which basically looks like this (full MWE): \documentclass[a4paper]{article} \usepackage{tikz} \usetikzlibrary{external} \newenvironment{mytikz}{%begin code ...
8
votes
2answers
170 views

How does expansion matter?

\newcount\@repeat% \def\repeat#1#2{% \@repeat#1\relax% \ifnum#1>\z@\relax% \advance\@repeat by -1\relax% \repeat{\@repeat}{#2}#2% \fi}% \repeat{2}{1}\\% \repeat{11}{f}\\% ...