Ruby bindings for libgweather, locations and weather for GNOME.
require "libgweather"
world = GWeather::Location.world
london = world.find_by_country_code("GB").find_nearest_city(51.5072, -0.1276)
info = GWeather::Info.new
info.location = london
# libgweather requires both of these before it will fetch: the weather
# services it talks to want to know who is asking.
info.application_id = "org.example.Weather"
info.contact_info = "mailto:you@example.com"
info.signal_connect("updated") { puts info.temp }
info.updateThe library ships a GObject Introspection typelib — GWeather-4.0.typelib — describing
every class, method, property and signal it has. GWeather::Loader, about twenty
lines, hands that to ruby-gnome's GObjectIntrospection::Loader, which defines
the Ruby classes from it at require time.
So this gem is pure Ruby: no extension of its own, no Cargo workspace, no per-platform binary. You get the whole library rather than the subset somebody got round to wrapping by hand, and it does not drift when the library gains API.
Be precise about install, though: gem install libgweather still compiles C, because
gobject-introspection and glib2 are themselves native extensions built
against glib, so a compiler and glib's development headers are needed. What
this gem adds on top is nothing — those two are what every ruby-gnome
application already has, since gtk4 depends on them.
The typelib is a C-library artefact, so it belongs to your distribution and this gem cannot install it:
| Debian / Ubuntu | gir1.2-gweather-4.0 |
| Fedora | libgweather |
| Arch | libgweather |
| nix | pkgs.libgweather |
If it is not in the default search path, point GI_TYPELIB_PATH at the
directory holding GWeather-4.0.typelib. The dev shell in flake.nix does this.
The typelib is not quite the whole story. libgweather also installs a
GSettings schema, org.gnome.GWeather4, which GWeather::Info reads on
construction — that is where the default unit preferences and the enabled
provider list come from. A missing schema is not an exception you can rescue:
GSettings calls g_error and takes the process with it —
GLib-GIO-ERROR **: No GSettings schemas are installed on the system
On a distribution the package above installs the schema into the system
directory and compiles it, so there is nothing to do. Under nix the schema is
in a per-package directory, so GSETTINGS_SCHEMA_DIR has to point at it; the
dev shell does that with glib.getSchemaPath.
One trap worth knowing. The typelib must come from the same glib build as
the gobject-introspection gem. Mixing two registers GIO twice in one process
and fails with cannot register existing type 'GTlsCertificate'. Under nix,
take both from one nixpkgs — and note that glib's typelibs live in its out
output, not the default one.
The gem needs GWeather-4.0.typelib and everything that typelib declares, resolved
transitively by the loader at require time. A missing one surfaces as
Typelib file for namespace 'X' not found, one at a time, so the whole chain
is listed here rather than discovered by repeated failure:
pkgs.libgweather— its typelib, which is whereGWeather-4.0.typeliblivespkgs.glib— GLib-2.0, GObject-2.0 and Gio-2.0, which nearly every GNOME typelib declares
Note the .out: a package's default output is often bin, which carries no
typelibs. makeSearchPath takes the first output, so it has to be asked for
out explicitly — this is the single most common way to get a search path that
looks right and finds nothing.
{
inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
outputs = { nixpkgs, ... }:
let
system = "x86_64-linux";
pkgs = nixpkgs.legacyPackages.${system};
typelibPath = pkgs.lib.makeSearchPath "lib/girepository-1.0"
(map (drv: drv.out or drv) [ pkgs.libgweather pkgs.glib ]);
in
{
devShells.${system}.default = pkgs.mkShell {
packages = [ pkgs.ruby_3_4 pkgs.bundler ] ++ [ pkgs.libgweather pkgs.glib ];
shellHook = ''
export GI_TYPELIB_PATH="${typelibPath}''${GI_TYPELIB_PATH:+:$GI_TYPELIB_PATH}"
'';
};
};
}Everything must come from one nixpkgs. A typelib built against a different
glib than the gobject-introspection gem registers GIO twice in the process
and fails with cannot register existing type 'GTlsCertificate'.
If you are packaging an application rather than entering a shell, the same
typelibPath goes on the wrapper:
makeWrapper ${ruby}/bin/ruby $out/bin/my-app \
--set GI_TYPELIB_PATH "${typelibPath}"nix develop
bin/testgem kit releaseThat is the whole thing. It gates on the changelog having an entry for this version, on no deprecation deadline coming due, and on a clean working tree; then builds, pushes and tags.
There is nothing to wait for in CI. This gem is pure Ruby, so gem build
produces one libgweather-X.Y.Z.gem that is the same artefact wherever it is built —
no extension, no per-platform gems, nothing for a workflow to hand back.
Apache-2.0. The library itself keeps its own licence; this gem links nothing and copies no code from it — it reads a description of it at runtime.