Ruby bindings for GExiv2, gexiv2, reading and writing the EXIF, IPTC and XMP metadata in an image.
require "gexiv2"
GExiv2.constants.size # the whole namespace, from the typelibgexiv2_0_16 ships a GObject Introspection typelib that describes every class,
method, property and signal it has. GExiv2::Loader — twenty lines — hands that
typelib 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 gexiv2_0_16 gains API.
It is worth being precise about what that does and does not buy you at install
time. gem install gexiv2 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 of that is
nothing: those two are what every ruby-gnome application already has, since
gtk4 depends on them. If you are writing a Ruby GTK app, gexiv2 costs you no
build step you were not already paying.
This is how ruby-gnome itself ships gtksourceview5, libsecret and the rest.
The nixpkgs attribute carries an explicit ABI version: plain gexiv2 was removed, and asking for it errors with "use a 'gexiv2_*' attribute with an explicit ABI version instead". gexiv2_0_16 ships GExiv2-0.16; gexiv2_0_10 ships GExiv2-0.10 for an older ABI.
The typelib is a C-library artefact, so it belongs to your distribution and this gem cannot install it:
| Debian / Ubuntu | gir1.2-gexiv2-0.16 |
| Fedora | gexiv2 |
| Arch | gexiv2 |
| nix | pkgs.gexiv2_0_16 |
If it is not in the default search path, point GI_TYPELIB_PATH at the
directory holding GExiv2-0.16.typelib. The dev shell in flake.nix does this.
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 are in its out
output, not the default bin one.
The gem needs GExiv2-0.16.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.gexiv2_0_16— its typelib, which is whereGExiv2-0.16.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.${system};
typelibPath = pkgs.lib.makeSearchPath "lib/girepository-1.0"
(map (drv: drv.out or drv) [ pkgs.gexiv2_0_16 pkgs.glib ]);
in
{
devShells.${system}.default = pkgs.mkShell {
packages = [ pkgs.ruby_3_4 pkgs.bundler ] ++ [ pkgs.gexiv2_0_16 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 gexiv2-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. gexiv2_0_16 itself is LGPL-2.1-or-later; this gem links nothing and copies no gexiv2_0_16 code — it reads a description of it at runtime.