POSIXGIOchar *pathGFile *filestruct stat *bufGFileInfo *infostruct statvfs *bufGFileInfo *infoint fdGInputStream *inGOutputStream *outDIR *GFileEnumerator *enumfstab entryGUnixMountPoint *mount_pointmtab entryGUnixMountEntry *mount_entry GnomeVFSGIOGnomeVFSURIGFileGnomeVFSFileInfoGFileInfoGnomeVFSResultGError, with G_IO_ERROR valuesGnomeVFSHandle & GnomeVFSAsyncHandleGInputStream or GOutputStreamGnomeVFSDirectoryHandleGFileEnumeratormime typecontent typeGnomeVFSMonitorGFileMonitorGnomeVFSVolumeMonitorGVolumeMonitorGnomeVFSVolumeGMountGnomeVFSDriveGVolume-GDriveGnomeVFSContextGCancellablegnome_vfs_async_cancelg_cancellable_cancel

The handling of trashed files has been changed in GIO, compared to gnome-vfs. gnome-vfs has a home-grown trash implementation that predates the freedesktop.org Desktop Trash Can specification that is implemented in GIO. The location for storing trashed files has changed from $HOME/.Trash to $HOME/.local/share/Trash (or more correctly $XDG_DATA_HOME/Trash), which means that there is a need for migrating files that have been trashed by gnome-vfs to the new location. In gnome-vfs, the trash:// scheme offering a merged view of all trash directories was implemented in nautilus, and trash-handling applications had to find and monitor all trash directories themselves. With GIO, the trash:// implementation has been moved to gvfs and applications can simply monitor that location: static void file_changed (GFileMonitor *file_monitor, GFile *child, GFile *other_file, GFileMonitorEvent event_type, gpointer user_data) { switch (event_type) { case G_FILE_MONITOR_EVENT_DELETED: g_print ("'%s' removed from trash\n", g_file_get_basename (child)); break; case G_FILE_MONITOR_EVENT_CREATED: g_print ("'%s' added to trash\n", g_file_get_basename (child)); break; default: ; } } static void start_monitoring_trash (void) { GFile *file; GFileMonitor *monitor; file = g_file_new_for_uri ("trash://"); monitor = g_file_monitor_directory (file, 0, NULL, NULL); g_object_unref (file); g_signal_connect (monitor, "changed", G_CALLBACK (file_changed), NULL); /* ... */ } GIO exposes some useful metadata about trashed files. There are trash::orig-path and trash::deletion-date attributes. The standard::icon attribute of the trash:// itself provides a suitable icon for displaying the trash can on the desktop. If you are using this icon, make sure to monitor this attribute for changes, since the icon may be updated to reflect that state of the trash can. Moving a file to the trash is much simpler with GIO. Instead of using gnome_vfs_find_directory() with %GNOME_VFS_DIRECTORY_KIND_TRASH to find out where to move the trashed file, just use the g_file_trash() function.

gnome-vfs has the dreaded gnome_vfs_xfer_uri_list() function which has tons of options and offers the equivalent of cp, mv, ln, mkdir and rm at the same time. GIO offers a much simpler I/O scheduler functionality instead, that lets you schedule a function to be called in a separate thread, or if threads are not available, as an idle in the mainloop. See g_io_scheduler_push_job().

gnome-vfs offered a way to monitor the association between mime types and default handlers for changes, with the #GnomeVFSMIMEMonitor object. GIO does not offer a replacement for this functionality at this time, since we have not found a compelling use case where #GnomeVFSMIMEMonitor was used. If you think you have such a use case, please report it at bugzilla.gnome.org.

Converting individual applications and their settings from GConf to GSettings can be done at will. But desktop-wide settings like font or theme settings often have consumers in multiple modules. Therefore, some consideration has to go into making sure that all users of a setting are converted to GSettings at the same time or that the program responsible for configuring that setting continues to update the value in both places. It is always a good idea to have a look at how others have handled similar problems before. An examplaric conversion can be found e.g. in the gsettings-tutorial branch of gnome-utils.

Conceptually, GConf and GSettings are fairly similar. Both have a concept of pluggable backends. Both keep information about keys and their types in schemas. Both have a concept of mandatory values, which lets you implement lock-down. There are some differences in the approach to schemas. GConf installs the schemas into the database and has API to handle schema information (gconf_client_get_default_from_schema(), gconf_value_get_schema(), etc). GSettings on the other hand assumes that an application knows its own schemas, and does not provide API to handle schema information at runtime. GSettings is also more strict about requiring a schema whenever you want to read or write a key. To deal with more free-form information that would appear in schema-less entries in GConf, GSettings allows for schemas to be 'relocatable'. One difference in the way applications interact with their settings is that with GConf you interact with a tree of settings (ie the keys you pass to functions when reading or writing values are actually paths with the actual name of the key as the last element. With GSettings, you create a GSettings object which has an implicit prefix that determines where the settings get stored in the global tree of settings, but the keys you pass when reading or writing values are just the key names, not the full path.

Most people use GConf via the high-level #GConfClient API. The corresponding API is the #GSettings object. While not every GConfClient function has a direct GSettings equivalent, many do: GConfClientGSettingsgconf_client_get_default()no direct equivalent, instead you call g_settings_new() for the schemas you usegconf_client_set()g_settings_set()gconf_client_get()g_settings_get()gconf_client_get_bool()g_settings_get_boolean()gconf_client_set_bool()g_settings_set_boolean()gconf_client_get_int()g_settings_get_int()gconf_client_set_int()g_settings_set_int()gconf_client_get_float()g_settings_get_double()gconf_client_set_float()g_settings_set_double()gconf_client_get_string()g_settings_get_string()gconf_client_set_string()g_settings_set_string()gconf_client_get_list()for string lists, see g_settings_get_strv(), else see g_settings_get_value() and #GVariant APIgconf_client_set_list()for string lists, see g_settings_set_strv(), else see g_settings_set_value() and #GVariant APIgconf_entry_get_is_writable()g_settings_is_writable()gconf_client_notify_add()not required, the #GSettings::changed signal is emitted automaticallygconf_client_add_dir()not required, each GSettings instance automatically watches all keys in its path#GConfChangeSetg_settings_delay(), g_settings_apply()gconf_client_get_default_from_schema()no equivalent, applications are expected to know their schemagconf_client_all_entries()no equivalent, applications are expected to know their schema, and GSettings does not allow schema-less entriesgconf_client_get_without_default()no equivalent There is a pattern that is sometimes used for GConf, where a setting can have explicit 'value A', explicit 'value B' or 'use the system default'. With GConf, 'use the system default' is sometimes implemented by unsetting the user value. This is not possible in GSettings, since it does not have API to determine if a value is the default and does not let you unset values. The recommended way (and much clearer) way in which this can be implemented in GSettings is to have a separate 'use-system-default' boolean setting.

GConf requires you to call gconf_client_add_dir() and gconf_client_notify_add() to get change notification. With GSettings, this is not necessary; signals get emitted automatically for every change. The #GSettings::changed signal is emitted for each changed key. There is also a #GSettings::change-event signal that you can handle if you need to see groups of keys that get changed at the same time. GSettings also notifies you about changes in writability of keys, with the #GSettings::writable-changed signal (and the #GSettings::writable-change-event signal).

GConf has a a concept of a set of changes which can be applied or reverted at once: #GConfChangeSet (GConf doesn't actually apply changes atomically, which is one of its shortcomings). Instead of a separate object to represent a change set, GSettings has a 'delayed-apply' mode, which can be turned on for a GSettings object by calling g_settings_delay(). In this mode, changes done to the GSettings object are not applied - they are still visible when calling g_settings_get() on the same object, but not to other GSettings instances or even other processes. To apply the pending changes all at once (GSettings does atomicity here), call g_settings_apply(). To revert the pending changes, call g_settings_revert() or just drop the reference to the #GSettings object.

If you are porting your application from GConf, most likely you already have a GConf schema. GIO comes with a commandline tool gsettings-schema-convert that can help with the task of converting a GConf schema into an equivalent GSettings schema. The tool is not perfect and may need assistence in some cases. Running gsettings-schema-convert --gconf --xml --schema-id "org.gnome.font-rendering" --output org.gnome.font-rendering.gschema.xml destop_gnome_font_rendering.schemas on the following desktop_gnome_font_rendering.schemas file: /schemas/desktop/gnome/font_rendering/dpi /desktop/gnome/font_rendering/dpi gnome int 96 DPI The resolution used for converting font sizes to pixel sizes, in dots per inch. ]]> produces a org.gnome.font-rendering.gschema.xml file with the following content: 96

DPI

The resolution used for converting font sizes to pixel sizes, in dots per inch. ]]> GSettings schemas are identified at runtime by their id (as specified in the XML source file). It is recommended to use a dotted name as schema id, similar in style to a DBus bus name, e.g. "org.gnome.font-rendering". The filename used for the XML schema source is immaterial, but schema compiler expects the files to have the extension .gschema.xml. It is recommended to simply use the schema id as the filename, followed by this extension, e.g. org.gnome.font-rendering.gschema.xml. The XML source file for your GSettings schema needs to get installed into $datadir/glib-2.0/schemas, and needs to be compiled into a binary form by the gschema-compile utility. GIO provides variables gsettingsschemadir and gsettingsupdateschemacache for the location and the command, which can be used in configure.in as follows: AC_SUBST(gsettingsschemadir, `pkg-config --variable gsettingsschemadir gio-2.0`) AC_SUBST(gsettingsupdateschemacache, `pkg-config --variable gsettingsupdateschemacache gio-2.0`) The corresponding Makefile.am fragment looks like this: gsettingsschema_DATA = my.app.gschema.xml install-data-hook: $(gsettingsupdateschemacache) $(gsettingsschemadir) One possible pitfall in doing schema conversion is that the default values in GSettings schemas are parsed by the #GVariant parser. This means that strings need to include quotes in the XML. Also note that the types are now specified as #GVariant type strings. string rgb ]]> becomes 'rgb' ]]> Another possible complication is that GConf specifies full paths for each key, while a GSettings schema has a 'path' attribute that contains the prefix for all the keys in the schema, and individual keys just have a simple name. So /schemas/desktop/gnome/font_rendering/antialiasing ]]> becomes ]]> Default values can be localized in both GConf and GSettings schemas, but GSettings uses gettext for the localization. You can specify the gettext domain to use in the gettext-domain attribute. Therefore, when converting localized defaults in GConf, /schemas/apps/my_app/font_size 18 24 ]]> becomes ... 18 ]]> Note how we used the context attribute to add msgctxt - "18" is not a good string to look up in gettext by itself. Also note that the value 24 is not present in the schema anymore. It has to be added to the gettext catalog for "be" instead. GSettings schemas have optional summary and description elements for each key which correspond to the short and long elements in the GConf schema and will be used in similar ways by a future gsettings-editor, so you should use the same conventions for them: The summary is just a short label with no punctuation, the description can be one or more complete sentences. Translations for these strings will also be handled via gettext, so you should arrange for these strings to be extracted into your gettext catalog. GSettings is a bit more restrictive about key names than GConf. Key names in GSettings can be at most 32 characters long, and must only consist of lowercase characters, numbers and dashes, with no consecutive dashes. The first character must not be a number or dash, and the last character cannot be '-'. If you are using the GConf backend for GSettings during the transition, you may want to keep your key names the same they were in GConf, so that existing settings in the users GConf database are preserved. You can achieve this by using the --allow-any-name with the gschema-compile schema compiler. Note that this option is only meant to ease the process of porting your application, allowing parts of your application to continue to access GConf and parts to use GSettings. By the time you have finished porting your application you must ensure that all key names are valid.

GConf comes with a GSettings backend that can be used to facility the transition to the GSettings API until you are ready to make the jump to a different backend (most likely dconf). To use it, you need to set the GSETTINGS_BACKEND to 'gconf', e.g. by using g_setenv ("GSETTINGS_BACKEND", "gconf", TRUE); early on in your program. Note that this backend is meant purely as a transition tool, and should not be used in production. GConf also comes with a utility called gsettings-data-convert, which is designed to help with the task of migrating user settings from GConf into another GSettings backend. It can be run manually, but it is designed to be executed automatically, every time a user logs in. It keeps track of the data migrations that it has already done, and it is harmless to run it more than once. To make use of this utility, you must install a keyfile in the directory /usr/share/GConf/gsettings which lists the GSettings keys and GConf paths to map to each other, for each schema that you want to migrate user data for. Here is an example: The last key demonstrates that it may be necessary to modify the key name to comply with stricter GSettings key name rules. Of course, that means your application must use the new key names when looking up settings in GSettings. The last group in the example also shows how to handle the case of 'relocatable' schemas, which don't have a fixed path. You can specify the path to use in the group name, separated by a colon. There are some limitations: gsettings-data-convert does not do any transformation of the values. And it does not handle complex GConf types other than lists of strings or integers.