# LaTeX allows line break between concluding em-dash and comma before a new sub clause begins

I am surprised by LaTeX putting a comma which follows an em-dash on a new line when the previous line is flushed. My intuition and sense of style tells me that they should never be separated. For example:

\documentclass[a4paper]{book}
\usepackage[top=35mm, bottom=38mm, inner=40mm, outer=24mm]{geometry}
\usepackage[UKenglish]{babel}

\begin{document}

Foo bar. The erosion responsible for ‘residuals’ is less related to the material process of
creation---e.g., rewriting in the sense of Mondrian or blurring the edges in the sense of
Rothko---, but to the double nature of time\ldots

\end{document}


Why isn't the second line ending with em-dash and comma? Is this the correct way you would break lines in (British) English?

• To begin with, one should ask whether “—,” is good style. – egreg Nov 2 '13 at 0:14
• em-dash insertions are integral part of my style. So yes, one can ask that question, but if we accept this possibility, why is the line break so odd? – Emit Taste Nov 2 '13 at 0:15
• Any ligature ending with a hyphen - inserts a discretionary break. Use \textemdash, which doesn't suffer from the problem. I'd simply avoid the case by not thinking to it in the first place. But the document is yours. – egreg Nov 2 '13 at 0:17
• Here is an interesting answer to whether "---," is good style. First of all, it confirms my feel that em-dash and comma are complementary elements and can occur together. On the other hand, the examples place the comma before the insertion. Can someone with native English confirm whether this is the preferred punctuation? My German genes want me to put the comma after the insertion... – Emit Taste Nov 2 '13 at 0:26
• @EmitTaste In the given sntence, "but" should be "than" and no comma is required in the constriction "less ... than ...". Thus, only the emdashes are required. I think of a comma as a point where a pause would be introduced in speaking, so even if a grammatical consruction would seem to require a comma, the pause already introduced by the emdash would remove the need for a comma. Visually, the emdash-comma comination is jarring to my Germanic/American/English sensibilities. I would rewrite the sentence in preference to using it. – Dan Nov 2 '13 at 5:28

## 1 Answer

You're being very unlucky, since a comma is really a thin character. You'll probably avoid all those cases by loading microtype.

However, if you want to be on the safe side, type \textemdash, which will not add a discretionary break, as explained in answers to Hyphenation problem with --- versus \textemdash

The output with microtype, with no change in the input, is the same as with \textemdash,; of course, microtype has other benefits.