{expansion} is about expanding tokens, including the manipulation of expansion order and the suppressing of expansion.
10
votes
2answers
563 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 ...
10
votes
3answers
135 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
267 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
194 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
3answers
220 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
1answer
87 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
1answer
400 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 ...
10
votes
1answer
309 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
253 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
573 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
404 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
1answer
184 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
1answer
130 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
241 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
1answer
1k 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 ...
9
votes
1answer
63 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 ...
9
votes
1answer
636 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
1answer
558 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
6answers
521 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}}
...
8
votes
4answers
248 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
122 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
384 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
2answers
172 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
58 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 ...
8
votes
2answers
269 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
84 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
166 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
2answers
1k 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
1answer
169 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 ...
8
votes
2answers
134 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:
...
8
votes
2answers
445 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 ...
8
votes
2answers
237 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 ...
8
votes
3answers
401 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 ...
8
votes
1answer
100 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
103 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 ...
8
votes
1answer
299 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 ...
8
votes
2answers
242 views
reversing the order of expansion
Is there a non-expl3 expandable function for reversing the order of expansion of an arbitrary number of tokens or macros? For example,
\reverseexpansion<n>\a\b
...
8
votes
0answers
98 views
Can I detect (from within a macro) if I'm in an \edef (or similar)? [duplicate]
Possible Duplicate:
Are we inside an edef?
I've defined a macro that changes its behaviour depending on the next character, so it uses \@ifnextchar. This makes it behave badly inside ...
7
votes
2answers
105 views
Is there a way of defining a command \nullifyifmoved{arg} that will normally act like its argument but act like a no-op if the macro is “moved”?
I'm interested in a macro \nullifyifmoved that takes one argument arg and acts like arg in normal contexts, except it acts like a no-op wherever it is written to a file. Some background:
Martin ...
7
votes
2answers
260 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 ...
7
votes
3answers
462 views
\aftergroup a list of tokens
\aftergroup executes the next token after the end of the current group. Is there a variant, \Vaftergroup{\some\tokens\a\b} that would put \some\tokens\a\b after the current group ends? Of course, one ...
7
votes
2answers
281 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 ...
7
votes
1answer
127 views
\ifmmode self-contradictory in amsmath (OK in just LaTeX)
File:
\documentclass[11pt]{article}
\usepackage{amsmath}
\newcommand{\argghhh}{\relax\ifmmode\bar\else\expandafter\=\fi}
\begin{document}
$ \argghhh a $
\end{document}
produces error (but ...
7
votes
3answers
163 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 ...
7
votes
2answers
126 views
How to put a conditional construct in \edef
\ifthenelse works fine normally, but when used in \edef:
\documentclass{article}
\usepackage{ifthen}
\newcommand\testing[1][]{%
\edef\tmp{\ifthenelse{\equal{#1}{}}{Blank}{#1}}%
}
\begin{document}
...
7
votes
2answers
399 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]{%
...
7
votes
4answers
400 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 ...
7
votes
1answer
220 views
Replacement for \unexpanded without eTeX extension
As comment on Can the extended register pool be used for \newinsert?, there is a reference to Dealing with tons of floats. It is interesting but uses \unexpanded:
\edef\@freelist{%
...
7
votes
1answer
137 views
expansion of loop macro
I have a macro that contains a loop using \@for and it works until I try to write its output to a file. The following document shows the problem.
\documentclass{article}
\makeatletter
...
7
votes
1answer
181 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 ...
