Why do \large and \textbf require different usage of braces?

Question

\large and other font size commands need to be placed inside a group:

In this text {\large some part} is large.

Whereas \textbf and other styling commands receive a parameter:

In this text \textbf{some part} is bold.

Why the difference?

\large is a switch, whereas \textbf{...} is a command with an argument. The corresponding switch is \bfseries. Actually \textbf{...} is the same as {\bfseries ...} — Bernard, Jun 07 '19 at 17:04
Related, although the present question is phrased more clearly: Braces inside or outside? — barbara beeton, Jun 07 '19 at 18:14

score 7 · Accepted Answer · answered Jun 07 '19 at 17:06

\textbf{stuff} (roughly) does {\bfseries stuff}, which is the counterpart for \large you are looking for. \textbf is defined in terms of \bfseries with:

\DeclareTextFontCommand{\textbf}{\bfseries}

You can do the same to create a \textlarge:

\documentclass{article}
\DeclareTextFontCommand{\textlarge}{\large}
\begin{document}
In this text \textlarge{some part} is large.
\end{document}

Why do \large and \textbf require different usage of braces?

1 Answers1