Gio.SettingsSchema

Fields

None

Methods

  get_id ()
  get_key (name)
  get_path ()
  has_key (name)
  list_children ()
  list_keys ()
  ref ()
  unref ()

Details

class Gio.SettingsSchema

The Gio.SettingsSchemaSource and Gio.SettingsSchema APIs provide a mechanism for advanced control over the loading of schemas and a mechanism for introspecting their content.

Plugin loading systems that wish to provide plugins a way to access settings face the problem of how to make the schemas for these settings visible to Gio.Settings. Typically, a plugin will want to ship the schema along with itself and it won’t be installed into the standard system directories for schemas.

Gio.SettingsSchemaSource provides a mechanism for dealing with this by allowing the creation of a new ‘schema source’ from which schemas can be acquired. This schema source can then become part of the metadata associated with the plugin and queried whenever the plugin requires access to some settings.

Consider the following example:

typedef struct
{
   ...
   GSettingsSchemaSource *schema_source;
   ...
} Plugin;

Plugin *
initialise_plugin (const gchar *dir)
{
  Plugin *plugin;

  ...

  plugin->schema_source =
    g_settings_schema_source_new_from_directory (dir,
      g_settings_schema_source_get_default (), FALSE, NULL);

  ...

  return plugin;
}

...

GSettings *
plugin_get_settings (Plugin      *plugin,
                     const gchar *schema_id)
{
  GSettingsSchema *schema;

  if (schema_id == NULL)
    schema_id = plugin->identifier;

  schema = g_settings_schema_source_lookup (plugin->schema_source,
                                            schema_id, FALSE);

  if (schema == NULL)
    {
      ... disable the plugin or abort, etc ...
    }

  return g_settings_new_full (schema, NULL, NULL);
}

The code above shows how hooks should be added to the code that initialises (or enables) the plugin to create the schema source and how an API can be added to the plugin system to provide a convenient way for the plugin to access its settings, using the schemas that it ships.

From the standpoint of the plugin, it would need to ensure that it ships a gschemas.compiled file as part of itself, and then simply do the following:

{
  GSettings *settings;
  gint some_value;

  settings = plugin_get_settings (self, NULL);
  some_value = g_settings_get_int (settings, "some-value");
  ...
}

It’s also possible that the plugin system expects the schema source files (ie: .gschema.xml files) instead of a gschemas.compiled file. In that case, the plugin loading system must compile the schemas for itself before attempting to create the settings source.

New in version 2.32.

get_id()[source]
Returns:the ID
Return type:str

Get the ID of self.

get_key(name)[source]
Parameters:name (str) – the name of a key
Returns:the Gio.SettingsSchemaKey for name
Return type:Gio.SettingsSchemaKey

Gets the key named name from self.

It is a programmer error to request a key that does not exist. See Gio.SettingsSchema.list_keys().

New in version 2.40.

get_path()[source]
Returns:the path of the schema, or None
Return type:str

Gets the path associated with self, or None.

Schemas may be single-instance or relocatable. Single-instance schemas correspond to exactly one set of keys in the backend database: those located at the path returned by this function.

Relocatable schemas can be referenced by other schemas and can therefore describe multiple sets of keys at different locations. For relocatable schemas, this function will return None.

New in version 2.32.

has_key(name)[source]
Parameters:name (str) – the name of a key
Returns:True if such a key exists
Return type:bool

Checks if self has a key named name.

New in version 2.40.

list_children()[source]
Returns:a list of the children on settings, in no defined order
Return type:[str]

Gets the list of children in self.

You should free the return value with GLib.strfreev() when you are done with it.

New in version 2.44.

list_keys()[source]
Returns:a list of the keys on self, in no defined order
Return type:[str]

Introspects the list of keys on self.

You should probably not be calling this function from “normal” code (since you should already know what keys are in your schema). This function is intended for introspection reasons.

New in version 2.46.

ref()[source]
Returns:a new reference to self
Return type:Gio.SettingsSchema

Increase the reference count of self, returning a new reference.

New in version 2.32.

unref()[source]

Decrease the reference count of self, possibly freeing it.

New in version 2.32.