6.12 Escrevendo notícias do canal

Channel authors may occasionally want to communicate to their users information about important changes in the channel. You’d send them all an email, but that’s not convenient.

Instead, channels can provide a news file; when the channel users run guix pull, that news file is automatically read and guix pull --news can display the announcements that correspond to the new commits that have been pulled, if any.

To do that, channel authors must first declare the name of the news file in their .guix-channel file:

(channel
  (version 0)
  (news-file "etc/news.txt"))

The news file itself, etc/news.txt in this example, must look something like this:

(channel-news
  (version 0)
  (entry (tag "the-bug-fix")
         (title (en "Fixed terrible bug")
                (fr "Oh la la"))
         (body (en "@emph{Good news}!  It's fixed!")
               (eo "Certe ĝi pli bone funkcias nun!")))
  (entry (commit "bdcabe815cd28144a2d2b4bc3c5057b051fa9906")
         (title (en "Added a great package")
                (ca "Què vol dir guix?"))
         (body (en "Don't miss the @code{hello} package!"))))

While the news file is using the Scheme syntax, avoid naming it with a .scm extension or else it will get picked up when building the channel and yield an error since it is not a valid module. Alternatively, you can move the channel module to a subdirectory and store the news file in another directory.

The file consists of a list of news entries. Each entry is associated with a commit or tag: it describes changes made in this commit, possibly in preceding commits as well. Users see entries only the first time they obtain the commit the entry refers to.

The title field should be a one-line summary while body can be arbitrarily long, and both can contain Texinfo markup (veja Overview em GNU Texinfo). Both the title and body are a list of language tag/message tuples, which allows guix pull to display news in the language that corresponds to the user’s locale.

If you want to translate news using a gettext-based workflow, you can extract translatable strings with xgettext (veja xgettext Invocation em GNU Gettext Utilities). For example, assuming you write news entries in English first, the command below creates a PO file containing the strings to translate:

xgettext -o news.po -l scheme -ken etc/news.txt

To sum up, yes, you could use your channel as a blog. But beware, this is not quite what your users might expect.