Shallow Thoughts : : 13

Akkana's Musings on Open Source Computing and Technology, Science, and Nature.

Thu, 13 Jan 2005

Nifty emacs hack: how to wrap only certain files

For a long time I've wanted some, but not all, text and html files to line-wrap automatically in emacs. For instance, it drives me nuts when I edit a system configuration file and it wraps each long line, or when I edit an html file containing lots of long links and it keeps wrapping between the <a and the href=. But for files which are mostly text (such as these blog entries), I want line wrapping.

I'd been trying to do this with html-mode-hook and text-mode-hook, then checking the filename and calling (auto-fill-mode) if appropriate, but it wasn't working, because buffer-file-name isn't always defined at the time the mode hook is called. (No one seems to know why.) The buffer name seems to be defined at that point, but it doesn't contain path information so I can't say "Use wrapping for anything under ~/Docs" or "Don't wrap anything in /etc".

But with some help from sachac and the nice folks on #emacs I came up with a much better solution, and it's way simpler than the mode-hook approach: derived modes.

I set up two new modes, called html-wrap-mode and text-wrap-mode, which are the same as html-mode and text-mode except that they turn on auto-fill. Then I use the easy auto-mode-alist mechanism, which already does string matching on the filename, to call these modes, instead of the regular text and html modes, based on the extension or some other aspect of the file's pathname. Here's what I added to .emacs:

;; Want auto-fill-mode for some text and html files, but not all.
;; So define two derived modes for that, and we'll use auto-mode-alist
;; to choose them based on filename.
(define-derived-mode html-wrap-mode html-mode "HTML wrap mode"
(define-derived-mode text-wrap-mode text-mode "Text wrap mode"

(setq auto-mode-alist
      (cons '("\\.blx$" . html-wrap-mode)
      (cons '("Docs/.*.html$" . html-wrap-mode)
      (cons '("Docs/" . text-wrap-mode)
            auto-mode-alist) ) ) )

Here's my current .emacs.

I wonder if vim has a way to do this?

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[ 23:30 Jan 13, 2005    More linux/editors | permalink to this entry | ]

Web pages with ugly fonts: Mozilla thinks they're Russian

For years I've been plagued by having web pages occasionally display in a really ugly font that looks like some kind of ancient OCR font blockily scaled up from a bitmap font.

For instance, look at West Valley College page, or this news page.

I finally discovered today that pages look like this because Mozilla thinks they're in Cyrillic! In the case of West Valley, their server is saying in the http headers:

Content-Type: text/html; charset=WINDOWS-1251
-- WINDOWS-1251 is Cyrillic -- but the page itself specifies a Western character set:
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">

On my system, Mozilla believes the server instead of the page, and chooses a Cyrillic font to display the page in. Unfortunately, the Cyrillic font it chooses is extremely bad -- I have good ones installed, and I can't figure out where this bad one is coming from, or I'd terminate it with extreme prejudice. It's not even readable for pages that really are Cyrillic.

The easy solution for a single page is to use Mozilla's View menu: View->Character Encoding->Western (ISO-8851-1). Unfortunately, that has to be done again for each new link I click on the site; there seems to be no way to say "Ignore this server's bogus charset claims".

The harder way: I sent mail to the contact address on the server page, and filed bug 278326 on Mozilla's ignoring the page's meta tag (which you'd think would override the server's default), but it was closed with the claim that the standard requires that Mozilla give precedence to the server. (I wonder what IE does?)

At least that finally inspired me to install Mozilla 1.8a6, which I'd downloaded a few days ago but hadn't installed yet, to verify that it saw the same charset. It did, but almost immediately I hit a worse bug: now mozilla -remote always opens a new window, even if new-tab or no directive at all is specified. The release notes have nothing matching "remote, but someone had already filed bug 276808.

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[ 20:15 Jan 13, 2005    More tech/web | permalink to this entry | ]