Given the requirements above, the package expression would become messy quickly:

```nix
{
  preFixup = ''
    for f in $(find $out/bin/ $out/libexec/ -type f -executable); do
      wrapProgram "$f" \
        --prefix GIO_EXTRA_MODULES : "${getLib dconf}/lib/gio/modules" \
        --prefix XDG_DATA_DIRS : "$out/share" \
        --prefix XDG_DATA_DIRS : "$out/share/gsettings-schemas/${name}" \
        --prefix XDG_DATA_DIRS : "${gsettings-desktop-schemas}/share/gsettings-schemas/${gsettings-desktop-schemas.name}" \
        --prefix XDG_DATA_DIRS : "${hicolor-icon-theme}/share" \
        --prefix GI_TYPELIB_PATH : "${
          lib.makeSearchPath "lib/girepository-1.0" [
            pango
            json-glib
          ]
        }"
    done
  '';
}
```

Fortunately, we have a [family of hooks]{#ssec-gnome-hooks-wrapgappshook} that automate this. They work in conjunction with other setup hooks that populate environment variables, and will then wrap all executables in `bin` and `libexec` directories using said variables.

- [`wrapGAppsHook3`]{#ssec-gnome-hooks-wrapgappshook3} for GTK 3 apps. For convenience, it also adds `dconf.lib` for a GIO module implementing a GSettings backend using `dconf`, `gtk3` for GSettings schemas, and `librsvg` for GdkPixbuf loader to the closure.
- [`wrapGAppsHook4`]{#ssec-gnome-hooks-wrapgappshook4} for GTK 4 apps. Same as `wrapGAppsHook3` but replaces `gtk3` with `gtk4`.
- [`wrapGAppsNoGuiHook`]{#ssec-gnome-hooks-wrapgappsnoguihook} for programs without a graphical interface. Same as the above but does not bring `gtk3` and `librsvg` into the closure.

The hooks do the the following:

- `wrapGApps*` hook itself will add the package’s `share` directory to `XDG_DATA_DIRS`.

- []{#ssec-gnome-hooks-glib} `glib` setup hook will populate `GSETTINGS_SCHEMAS_PATH` and then `wrapGApps*` hook will prepend it to `XDG_DATA_DIRS`.

- []{#ssec-gnome-hooks-gdk-pixbuf} `gdk-pixbuf` setup hook will populate `GDK_PIXBUF_MODULE_FILE` with the path to biggest `loaders.cache` file from the dependencies containing [GdkPixbuf loaders](#ssec-gnome-gdk-pixbuf-loaders). This works fine when there are only two packages containing loaders (`gdk-pixbuf` and e.g. `librsvg`) – it will choose the second one, reasonably expecting that it will be bigger since it describes extra loader in addition to the default ones. But when there are more than two loader packages, this logic will break. One possible solution would be constructing a custom cache file for each package containing a program like `services/x11/gdk-pixbuf.nix` NixOS module does. `wrapGApps*` hook copies the `GDK_PIXBUF_MODULE_FILE` environment variable into the produced wrapper.

- []{#ssec-gnome-hooks-gtk-drop-icon-theme-cache} One of `gtk3`’s setup hooks will remove `icon-theme.cache` files from package’s icon theme directories to avoid conflicts. Icon theme packages should prevent this with `dontDropIconThemeCache = true;`.

- []{#ssec-gnome-hooks-dconf} `dconf.lib` is a dependency of `wrapGApps*` hook, which then also adds it to the `GIO_EXTRA_MODULES` variable.

- []{#ssec-gnome-hooks-hicolor-icon-theme} `hicolor-icon-theme`’s setup hook will add icon themes to `XDG_ICON_DIRS`.

- []{#ssec-gnome-hooks-gobject-introspection} `gobject-introspection` setup hook populates `GI_TYPELIB_PATH` variable with `lib/girepository-1.0` directories of dependencies, which is then added to wrapper by `wrapGApps*` hook. It also adds `share` directories of dependencies to `XDG_DATA_DIRS`, which is intended to promote GIR files but it also [pollutes the closures](https://github.com/NixOS/nixpkgs/issues/32790) of packages using `wrapGApps*` hook.

- []{#ssec-gnome-hooks-gst-grl-plugins} Setup hooks of `gst_all_1.gstreamer` and `grilo` will populate the `GST_PLUGIN_SYSTEM_PATH_1_0` and `GRL_PLUGIN_PATH` variables, respectively, which will then be added to the wrapper by `wrapGApps*` hook.

You can also pass additional arguments to `makeWrapper` using `gappsWrapperArgs` in `preFixup` hook: