Shrink space after colon without shrinking space after period

Question

When a colon is used to separate clauses in a sentence (rather than preceding a list), current typographic practice, and my preference, is to follow it with the same space as after a semicolon.

The LaTeX default \nonfrenchspacing violates that, making the space after a colon the same as after a period.

But \frenchspacing,while shrinking the space after a colon, unfortunately also shrinks the space after a period, which I do not want to do.

See this example:

\documentclass[12pt]{article}
\begin{document}

\nonfrenchspacing
\emph{nonfrenchspacing}
\smallskip

Spacing after; semicolon.

Spacing after: colon.

Spacing after. period

\bigskip

\frenchspacing
\emph{frenchspacing}
\smallskip

Spacing after; semicolon.

Spacing after: colon.

Spacing after. period

\end{document}

How can I get all the following:

• space after a colon separating clauses the same as that after a semicolon; and
• space after a colon before a list retains the larger spacing from \nonfrenchspacing; and
• space after a period retains the larger spacing from \nonfrenchspacing?

Answer 1

If you want that the space after a colon is the same as after a semicolon, tell TeX that the space factor codes of both are the same.

\documentclass[12pt]{article}
\begin{document}

\nonfrenchspacing\sfcode`:=\sfcode`;
\emph{nonfrenchspacing}
\smallskip

Spacing after; semicolon.

Spacing after: colon.

Spacing after. period

\bigskip

\frenchspacing
\emph{frenchspacing}
\smallskip

Spacing after; semicolon.

Spacing after: colon.

Spacing after. period

\end{document}

Since you won't be changing between “French spacing” and “non French spacing” (would you?), you can simply state

\sfcode`:=\sfcode`;

before \begin{document}.

\documentclass[12pt]{article}

\sfcode`:=\sfcode`;

\begin{document}

Spacing after; x

Spacing after: x

Spacing after. x

\end{document}

TeXnical note. The space factors of semicolon, colon and period under \nonfrenchspacing are, respectively, 1500, 2000 and 3000. So it's a bit inaccurate to say that the space after a colon is the same as after a period.