babel + hyperref: »redefining shorthand« several times per page

Question

consider the following code:

\documentclass{article}
\usepackage[ngerman]{babel}
\usepackage{hyperref}
\usepackage{blindtext}

\begin{document}
\Blindtext\Blindtext\Blindtext
\Blindtext\Blindtext\Blindtext
\end{document}

...and a small piece from its logfile.

[3]
Package babel Info: Redefining ngerman shorthand "|
(babel)             in language  on input line 7.
Package babel Info: Redefining ngerman shorthand "~
(babel)             in language  on input line 7.
Package babel Info: Redefining ngerman shorthand "|
(babel)             in language  on input line 7.
Package babel Info: Redefining ngerman shorthand "~
(babel)             in language  on input line 7.
Package babel Info: Redefining ngerman shorthand "|
(babel)             in language  on input line 7.
Package babel Info: Redefining ngerman shorthand "~
(babel)             in language  on input line 7.

babel seems to redefine these shorthands several times per page, even when there's nothing but plain text (why does it do so?). This happens only if hyperref is active. Half of that logfile consists of nothing but iterations of these lines. Obviously, it's even worse in the 350-page document that I'm currently working on, making troubleshooting a real pain in the neck. Is there a way to prevent this bloating?

Answer 1

The info comes from \pdfstringdef, which is used to convert a TeX string to a PDF bookmark string. \pdfstringdef redefines many, many commands to disable them, to provide replacements. Thus hyperref also redefines some shorthands. For example, TeX's hyphenation is irrelevant for bookmarks, thus hyperref redefines the shorthands for ngerman regarding hyphenation:

\declare@shorthand{ngerman}{"|}{}%
\declare@shorthand{ngerman}{"~}{-}%

Two info messages are generated, each time \pdfstringdef is invoked with \usepackage[ngerman]{babel}. This happens for \section and friends and some other occasions (setting of PDF information entries).

Answer 2

Once you know that such information is irrelevant (and it is), you can use gentle manners (also known as “the sledgehammer”) to silence it:

\documentclass{article}
\usepackage[ngerman]{babel}

\usepackage{lipsum}
\usepackage{etoolbox}

\usepackage{hyperref}

\makeatletter
\patchcmd{\@decl@short}{\bbl@info}{\@gobble}{}{}
\patchcmd{\@decl@short}{\bbl@info}{\@gobble}{}{}
\makeatother

\begin{document}
\lipsum[1-40]
\end{document}

No more Redefining ngerman shorthand message.

A more delicate patch would be

\documentclass{article}
\usepackage[ngerman]{babel}
\usepackage{lipsum}
\usepackage{etoolbox}

\usepackage{hyperref}

\makeatletter
\patchcmd{\pdfstringdef}
  {\csname HyPsd@babel@}
  {\let\bbl@info\@gobble\csname HyPsd@babel@}
  {}{}
\makeatother

\begin{document}
\lipsum[1-40]

\end{document}

that would disable \bbl@info (when redefining shorthands) only in the context of \pdfstringdef.