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Questions tagged [grouping]

{grouping} is about the grouping mechanism in TeX, and about local and global assignments.

113
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2answers
30k views

When should one use \begingroup instead of \bgroup?

Is there ever a case when the use of \begingroup is preferred to \bgroup? Obviously, \bgroup is necessary in cases where you need to have balanced braces and thus cannot use {, but when is it ...
38
votes
3answers
11k views

When to use @ in an \if statement

I am new to LaTeX and so this question might come across as rather basic. It might also reflect my biases/assumptions from my C/C++ programming days. I was seeing the code of the 'exam' class and ...
38
votes
1answer
3k views

] inside an optional argument

I accidentally discovered (here) that a closing square bracket within an optional argument delimited by [ ] can cause problems. Here is example code illustrating the issue: \documentclass{article} \...
35
votes
2answers
50k views

Temporarily increase line spacing

How do I temporarily increase line spacing? I have some text on my title page: \begin{center} { \Large \textbf{The Great Thesis About Some Very Great Things Indeed With a Pretty Long Title That Will ...
30
votes
2answers
5k views

What does \begingroup\expandafter…\endgroup do?

I often see code of the following form in package implementations (this example is from the LaTeX3 sources): \begingroup\expandafter\expandafter\expandafter\endgroup \expandafter\ifx\csname directlua\...
27
votes
4answers
2k views

Kerning between bold and non-bold text

I'd like to write a word in bold followed by a comma and a non-bold word, like this: \textbf{why}, blah If I just write why, TeX inserts a kern to shift the comma a little closer to the "y". But ...
24
votes
4answers
876 views

How do I get a value out of a group?

I've just recovered from my first real foray into LaTeX3 programming. It was ... an experience. Not a completely unpleasant one and once I'd gotten used to the syntax then I found it a lot easier ...
24
votes
3answers
8k views

Limit macro/newcommand scope to section

How can I limit the scope of a \newcommand to a \section? This is what I'd like to have: The command is defined only inside the \section, not globally; The command scope is that \section and cannot ...
24
votes
3answers
713 views

What are the effects of an empty group, {}?

In order to have a syntactic space after a no-argument command, one is taught to delimit the command token with an empty group ({}), like this: \somecommand{} more LaTeX material. However an empty ...
24
votes
1answer
3k views

Is there a way to have an “empty” environment to merely limit scope of declarations?

I am fairly new to LaTeX, so I apologize if this is a beginner question, but I have not found a good way to query for it otherwise. I have observed that when I use an environment like \begin{itemize}....
23
votes
4answers
1k views

Is there a way to set a *global* key value using `pgfkeys`?

The simple answer to this question appears to be "No"; quoting from the pgf manual: The setting of a key is always local to the current TeX group. However, this is very annoying because it means ...
23
votes
3answers
4k views

\global\renewcommand equivalent of \global\def

The following MWE works just fine, but I had to resort to using \global\def (not that there's anything wrong with it). The intent of the MWE is to provide access to the value of macro as set in an ...
21
votes
1answer
1k views

Global scope or permanent length or savebox

I am trying to save a minipage width and height in one environment, and use these dimensions in a subsequent environment of mine, to make a picture environment. The idea is to create a picture on the ...
19
votes
3answers
1k views

Should LaTeX counters always be modified globally?

In this answer, egreg states that "LaTeX counters should always be modified globally". However, the etoolbox package provides the \defcounter macro which will assign a value to a previously ...
19
votes
2answers
317 views

global confusion

Simply put, when should I care if something is global or not? What does this really mean? If my package, for example, provides \newcommand*{\setfooter}[1]{\def\mypackage@footer{#1}} And I later use ...
19
votes
1answer
2k views

Why is \global\let not always global?

As an LaTeX environment opens a local group, it is normally necessary to use a global definition if changes in the environment should be available after the environment: \documentclass{minimal} \...
18
votes
3answers
2k views

What is the difference between local and global in a TeX meaning?

In tikz declare function and babel french option it came to the question about the difference between local and global in a TeX meaning. In the liked question the babel shorthand ; should be ...
18
votes
2answers
524 views

Why do I have to put the center environment in a group for \@afterindentfalse\@afterheading to suppress indentation?

Consider the following two macros, the only difference being that one has the environment inside a group: \documentclass{article} \makeatletter \newcommand\thisworks{% {\begin{center} $\ast$ ...
17
votes
2answers
1k views

How to create *local* labels/refs in LaTeX?

Concise question: Is there any way to limit the scope in which a \label is visible to a \ref? Motivation: My current goal is to create a rather large document, containing many exercises and their ...
16
votes
3answers
1k views

Use \bgroup and \egroup to set some pre and post code to a macro

Why isn’t it possible to use \bgroup and \egroup in this way? \documentclass{article} \def\precode{\fbox\bgroup} \def\postcode{\egroup} \newcommand{\mymacro}[1]{\precode#1\postcode} \begin{...
16
votes
3answers
527 views

Restore kerning across empty groups

Context In my document, I attach a tooltip to the middle part of a word. To demonstrate this behavior, try mousing over just the letter V in the word AVA. Here is the implementation and usage of my \...
15
votes
2answers
378 views

How can own commands be aware of \global? [duplicate]

When I define a command that defines commands \def\makefoobar{ \def\foo{foo} \def\bar{bar} } and prefix it with \global { \global\makefoobar } it is treated like { \global\def\foo{foo} \...
15
votes
4answers
2k views

Is there a way of limiting the scope of \newlength?

Is there a way of limiting the scope of \newlength? I'm using the same name in many TikZ picture but each with different value, and I don't want it to live on between the pictures as it's not intended ...
15
votes
4answers
359 views

\tl_replace_all:Nnn recurse subgroups

Suppose I had a token list variable containing abc{ab{abc}c}. I want to replace every occurrence of b with d. As you can see there are subgroups containing b which I also want to have replaced, so ...
15
votes
2answers
1k views

Restrict macro to an environment

I am quite a noob when it comes to customising LaTeX/XeLaTeX. I would like to know if there's a way to limit the usage of a macro to a specific environment. Consider the following macro and ...
15
votes
1answer
364 views

First occurrence of a command

I'm writing some macros that need to behave differently after first occurrence. I decided to use the etoolbox package's toggle. My MWE is as follows: \documentclass{article} \usepackage{etoolbox} \...
14
votes
1answer
556 views

A curious dependency between \newcommand and curly braces

An example is a bit artificial, but the point is that I do not understand why {} influence the outcome of \newcommand in the way described below. Consider the following definition: \newcommand\...
14
votes
1answer
169 views

Difference between “hbox group” and “adjusted hbox group”?

eTeX's \currentgrouptype distinguishes two types of \hbox group types \hbox{\showthe\currentgrouptype} % 3 "adjusted hbox group" \noindent \hbox{\showthe\currentgrouptype} % 2 "hbox group" Looking ...
13
votes
4answers
2k views

When to use or avoid grouping?

For writing my own TeX code, grouping (\begingroup, \endgroup) helps on automatically saving and restoring TeX "variables". (La)TeX "variables" are either macros or registers. The registers can ...
13
votes
2answers
413 views

necessity of braces for accent commands

Many resources on LaTeX teach that "é" and "ä" are typeset with (respectively) \'{e} and \"{a}; and it is similar for other accent symbols. Are the braces really needed? Aren't \'e and \"a shorter but ...
13
votes
2answers
779 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: \begingroup\expandafter\expandafter\expandafter\...
13
votes
2answers
2k views

siunitx: How do I unset options previously set with \sisetup?

In the siunitx package (v1.3), I know that I can set various options with the \sisetup command. But what if I want a particular option to apply to only a small section of my document, with default ...
13
votes
1answer
2k views

Why do \setcounter and \addtocounter commands have global effect, while \setlength and \addtolength commands obey the normal scoping rules?

The \setcounter and \addtocounter commands have global effect, while the \setlength and \addtolength commands obey the normal scoping rules. Why were they designed like this? Why are \setcounter ...
13
votes
1answer
2k views

Splitting a command syntax across a \newenvironment definition

This question is a direct follow-up to the question Can a \newcommand Definition Contain Braces as Substitution Text? I asked yesterday. The following example is once again a counter-intuitive one, ...
12
votes
1answer
6k views

How to escape “]” in a description's item tag?

In a description like \begin{description} \item[\texttt{DoSomething(items[])}:] ... \end{description} , how do I escape the "]" character?
12
votes
1answer
696 views

What is the scope of elements of TikZ pictures?

I understand that named elements of a tikzpicture cannot be referenced before they are defined; but I'm confused about how "long" a named element persists. It appears that once named, an element ...
12
votes
2answers
1k views

Is there a way to limit the scope of \usepackage?

When I tried to use the breqn package suggested by an answer to the question How do I break a long equation over lines It managed to break a whole bunch of unrelated equations (equations that did ...
11
votes
3answers
2k views

Drawing a proper shadow for overlapping objects

I draw images that are composed of several overlapping nodes. If I add a drop shadow to each node, the shadow of the second node is drawn over the first node, as seen in the picture below (which ...
11
votes
3answers
537 views

Making register declarations local, Undefining a register (count, toks, etc.)

Is it possible to make \newcount, \newtoks, etc. respect grouping, so that, e.g., \newcount\temp\temp=2{\newcount\temp\temp=1}\showthe\temp gives 2 (instead of 0)? Relatedly, is it possible to ...
11
votes
2answers
287 views

What combinations of mode and \currentgrouptype exist?

I am trying to predict in any given situation what TeX does if a closing brace reaches its stomach (apart from reverting local assignments). For instance, \vbox{\tracingall H} shows that if it is in ...
11
votes
1answer
2k views

Creating temporary definitions for commands

In the context of writing something like homework solutions for a math class, I often face an awkward situation. Each problem will have some idiomatic functions that are cumbersome and error prone to ...
10
votes
3answers
722 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 ...
10
votes
2answers
1k views

How can I change the text color in such a way that the effect transcends groups?

I'd like to have a command \globalred that makes all subsequent text red, even if the command is issued inside a group. For example, the output of the TeX file \documentclass{article} \begin{document}...
10
votes
2answers
909 views

Beamer: content in box register does not survive \end{frame}

Consider the following example (I edited the example to include LaTeX lrbox environment): \documentclass{beamer} \newsavebox\mybox \newsavebox\myboxb \begin{document} \frame{ \sbox\mybox{Hello ...
10
votes
2answers
2k views

Is there a way to control scope of fontspec font change?

I would like to limit the scope of \fontspec to just one or a couple of words in my paragraph, for example: Vivamus gravida lacus a sapien \fontspec{The Font Name}{interdum} eget interdum mi sodales....
10
votes
2answers
2k views

\newtoks token seems to have local scope

I want to collect the first line of a quotation to use later. I have used \newtoks for a similar purpose so tried it here, this way: \documentclass[12pt] {article} \newtoks{\qfirstlineinternal} \...
9
votes
5answers
403 views

Environment as local namespaces

I wish for something quite simple to describe but maybe impossible to have. I would like to give multiple definitions to a macro (\U in my case) such that depending on the environment it can have ...
9
votes
3answers
167 views

Problems getting \expandafter\<controlsequence>\endgroup to work as expected

I have a scenario where I'm testing for a condition within a group which will then trigger inputting a corresponding outside file. The problem is that the outside file may contain control sequences ...
9
votes
3answers
4k views

LaTeX3: how to define a variable locally

I am trying to learn the LaTeX3 syntax. One of the questions I have come up with is how to define a variable, i. e. a macro without arguments in TeX parlance, with local scope within a group. In TeX ...
9
votes
2answers
5k views

\bgroup and \egroup?

So I've been looking to expand on the following bit of code (a hack to not screw up the margins when using oversized figures): \noindent\makebox[\textwidth]{% \begin{tabularx}{1.5\textwidth}{XX} \...