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# What’s new in babel 3.67

2021-11-29

## Executing code based on the selector

Sometimes a different setup is desired depending on the selector used, and \IfBabelSelectorTF{<selectors>}{<true>}{<false>} is provided for this purpose. Values allowed in <selectors> are select, other, foreign, other* (and also foreign* for the tentative starred version), and it can consist of a comma-separated list. For example:

\IfBabelSelectorTF{other, other*}{A}{B}


is true with these two environment selectors.

Its natural place of use is in hooks or in \extras<language>.

Bear in mind \selectlanguage can be automatically executed, in some cases, in the auxiliary files, at heads and foots, and after the environment otherlanguage*.

## Turning on and off transforms

Until now, the only way to turn on or off a feature was by switching the language, Now, you can associate a user defined transform to an attribute, so that it’s active only when it’s set (currently its attribute value is ignored). With this mechanism transforms can be set or unset even in the middle of paragraphs, and applied to single words.

To define, set and unset the attribute, the LaTeX kernel provides the macros \newattribute, \setattribute and \unsetattribute. Here is an example of how to use this feature:

\documentclass{article}

\usepackage[english]{babel}

\newattribute{\spcexclam} % Unset by default

\babelprehyphenation[attribute=\spcexclam]{english}{ {a}! }{
{},
{ insert, penalty = 10000 },
{ insert, space=.3 .05 0, data = 1 },
{}
}

\newcommand\withspc[1]{{\setattribute{\spcexclam}{1}#1}}
\newcommand\withoutspc[1]{{\unsetattribute{\spcexclam}#1}}

\begin{document}

Hello! \withspc{Hello!} Hol\withspc{a!} Hello\withspc{!} Hello!

\setattribute{\spcexclam}{1}

Hello! \withoutspc{Hello!} Hol\withoutspc{a!} Hello\withoutspc{!} Hello!

\end{document}


It will print:

Hello! Hello ! Hello ! Hello! Hello!
Hello ! Hello! Hello! Hello! Hello !

The transform is applied when the corresponding attribute is set in all nodes to be transformed, which explains why there is no space in the 4th ‘Hello’. The ‘context’ in the pattern, that is, the characters outside the group ()..(), when used, are not taken into account.

Transforms predefined in the ini locale files can be made attribute-dependent, too (in \babelprovide). When an attribute between parenthesis is inserted all subsequent transforms will be assigned to it (up to the list end or another attribute). For example, and provided an attribute called \withsigmafinal has been defined:

transforms = transliteration.omega (\withsigmafinal) sigma.final


This applies transliteration.omega always, but sigma.finalonly when \withsigmafinal is set.

## Transforms for Latin

They are defined in all variants.

digraphs.ligatures Replaces the groups ae, AE, oe, OE with æ, Æ, œ, Œ.

letters.noj Replaces j, J with i, I.

letters.uv Replaces v, U with u, V.