注: The functionality described here is a “technology preview” as of version eac2909. As such, the interface is subject to change.
Sometimes you might need to mix packages from the revision of Guix you’re currently running with packages available in a different revision of Guix. Guix inferiors allow you to achieve that by composing different Guix revisions in arbitrary ways.
Technically, an “inferior” is essentially a separate Guix process
connected to your main Guix process through a REPL (see 调用guix repl). The
(guix inferior) module allows you to create inferiors
and to communicate with them. It also provides a high-level interface to
browse and manipulate the packages that an inferior provides—inferior
When combined with channels (see 通道), inferiors provide a simple
way to interact with a separate revision of Guix. For example, let’s assume
you want to install in your profile the current
guile package, along
guile-json as it existed in an older revision of
Guix—perhaps because the newer
guile-json has an incompatible API
and you want to run your code against the old API. To do that, you could
write a manifest for use by
guix package --manifest (see Writing Manifests); in that manifest, you would create an inferior for that old
Guix revision you care about, and you would look up the
package in the inferior:
(use-modules (guix inferior) (guix channels) (srfi srfi-1)) ;for 'first' (define channels ;; This is the old revision from which we want to ;; extract guile-json. (list (channel (name 'guix) (url "https://git.savannah.gnu.org/git/guix.git") (commit "65956ad3526ba09e1f7a40722c96c6ef7c0936fe")))) (define inferior ;; An inferior representing the above revision. (inferior-for-channels channels)) ;; Now create a manifest with the current "guile" package ;; and the old "guile-json" package. (packages->manifest (list (first (lookup-inferior-packages inferior "guile-json")) (specification->package "guile")))
On its first run,
guix package --manifest might have to build the
channel you specified before it can create the inferior; subsequent runs
will be much faster because the Guix revision will be cached.
(guix inferior) module provides the following procedures to open
channels. Use the cache at cache-directory, where entries can be reclaimed after ttl seconds. This procedure opens a new connection to the build daemon.
As a side effect, this procedure may build or substitute binaries for channels, which can take time.
directory/command repl or equivalent. Return
if the inferior could not be launched.
The procedures listed below allow you to obtain and manipulate inferior packages.
Return the list of packages known to inferior.
name in inferior, with highest version numbers first. If version is true, return only packages with a version number prefixed by version.
Return true if obj is an inferior package.
These procedures are the counterpart of package record accessors (see 软件包引用). Most of them work by querying the inferior package comes from, so the inferior must still be live when you call these procedures.
Inferior packages can be used transparently like any other package or
file-like object in G-expressions (see G-表达式). They are also
transparently handled by the
packages->manifest procedure, which is
commonly used in manifests (see the
--manifest option of
guix package). Thus you can insert
an inferior package pretty much anywhere you would insert a regular package:
in manifests, in the
packages field of your
declaration, and so on.