#[repr(transparent)]
pub struct Application { /* private fields */ }
Expand description

A Application is the foundation of an application. It wraps some low-level platform-specific services and is intended to act as the foundation for higher-level application classes such as GtkApplication or MxApplication. In general, you should not use this class outside of a higher level framework.

GApplication provides convenient life cycle management by maintaining a “use count” for the primary application instance. The use count can be changed using ApplicationExt::hold() and ApplicationExt::release(). If it drops to zero, the application exits. Higher-level classes such as GtkApplication employ the use count to ensure that the application stays alive as long as it has any opened windows.

Another feature that GApplication (optionally) provides is process uniqueness. Applications can make use of this functionality by providing a unique application ID. If given, only one application with this ID can be running at a time per session. The session concept is platform-dependent, but corresponds roughly to a graphical desktop login. When your application is launched again, its arguments are passed through platform communication to the already running program. The already running instance of the program is called the “primary instance”; for non-unique applications this is always the current instance. On Linux, the D-Bus session bus is used for communication.

The use of Application differs from some other commonly-used uniqueness libraries (such as libunique) in important ways. The application is not expected to manually register itself and check if it is the primary instance. Instead, the main() function of a Application should do very little more than instantiating the application instance, possibly connecting signal handlers, then calling ApplicationExtManual::run(). All checks for uniqueness are done internally. If the application is the primary instance then the startup signal is emitted and the mainloop runs. If the application is not the primary instance then a signal is sent to the primary instance and ApplicationExtManual::run() promptly returns. See the code examples below.

If used, the expected form of an application identifier is the same as that of of a D-Bus well-known bus name. Examples include: com.example.MyApp, org.example.internal_apps.Calculator, org._7_zip.Archiver. For details on valid application identifiers, see id_is_valid().

On Linux, the application identifier is claimed as a well-known bus name on the user’s session bus. This means that the uniqueness of your application is scoped to the current session. It also means that your application may provide additional services (through registration of other object paths) at that bus name. The registration of these object paths should be done with the shared GDBus session bus. Note that due to the internal architecture of GDBus, method calls can be dispatched at any time (even if a main loop is not running). For this reason, you must ensure that any object paths that you wish to register are registered before Application attempts to acquire the bus name of your application (which happens in ApplicationExt::register()). Unfortunately, this means that you cannot use ApplicationExt::is_remote() to decide if you want to register object paths.

GApplication also implements the ActionGroup and ActionMap interfaces and lets you easily export actions by adding them with ActionMapExt::add_action(). When invoking an action by calling ActionGroupExt::activate_action() on the application, it is always invoked in the primary instance. The actions are also exported on the session bus, and GIO provides the DBusActionGroup wrapper to conveniently access them remotely. GIO provides a DBusMenuModel wrapper for remote access to exported GMenuModels.

There is a number of different entry points into a GApplication:

  • via ‘Activate’ (i.e. just starting the application)

  • via ‘Open’ (i.e. opening some files)

  • by handling a command-line

  • via activating an action

The signal::Application::startup signal lets you handle the application initialization for all of these in a single place.

Regardless of which of these entry points is used to start the application, GApplication passes some ‘platform data’ from the launching instance to the primary instance, in the form of a glib::Variant dictionary mapping strings to variants. To use platform data, override the before_emit or after_emit virtual functions in your Application subclass. When dealing with ApplicationCommandLine objects, the platform data is directly available via ApplicationCommandLineExt::cwd(), ApplicationCommandLineExt::environ() and ApplicationCommandLineExt::platform_data().

As the name indicates, the platform data may vary depending on the operating system, but it always includes the current directory (key “cwd”), and optionally the environment (ie the set of environment variables and their values) of the calling process (key “environ”). The environment is only added to the platform data if the ApplicationFlags::SEND_ENVIRONMENT flag is set. Application subclasses can add their own platform data by overriding the add_platform_data virtual function. For instance, GtkApplication adds startup notification data in this way.

To parse commandline arguments you may handle the signal::Application::command-line signal or override the local_command_line() vfunc, to parse them in either the primary instance or the local instance, respectively.

For an example of opening files with a GApplication, see gapplication-example-open.c.

For an example of using actions with GApplication, see gapplication-example-actions.c.

For an example of using extra D-Bus hooks with GApplication, see gapplication-example-dbushooks.c.

Implements

ApplicationExt, glib::ObjectExt, ActionGroupExt, ActionMapExt, ApplicationExtManual

Implementations

Creates a new Application instance.

If non-None, the application id must be valid. See id_is_valid().

If no application ID is given then some features of Application (most notably application uniqueness) will be disabled.

application_id

the application id

flags

the application flags

Returns

a new Application instance

Creates a new builder-pattern struct instance to construct Application objects.

This method returns an instance of ApplicationBuilder which can be used to create Application objects.

Returns the default Application instance for this process.

Normally there is only one Application per process and it becomes the default when it is created. You can exercise more control over this by using ApplicationExt::set_default().

If there is no default application then None is returned.

Returns

the default application for this process, or None

Checks if application_id is a valid application identifier.

A valid ID is required for calls to new() and ApplicationExt::set_application_id().

Application identifiers follow the same format as D-Bus well-known bus names. For convenience, the restrictions on application identifiers are reproduced here:

  • Application identifiers are composed of 1 or more elements separated by a period (.) character. All elements must contain at least one character.

  • Each element must only contain the ASCII characters [A-Z][a-z][0-9]_-, with - discouraged in new application identifiers. Each element must not begin with a digit.

  • Application identifiers must contain at least one . (period) character (and thus at least two elements).

  • Application identifiers must not begin with a . (period) character.

  • Application identifiers must not exceed 255 characters.

Note that the hyphen (-) character is allowed in application identifiers, but is problematic or not allowed in various specifications and APIs that refer to D-Bus, such as Flatpak application IDs, the DBusActivatable interface in the Desktop Entry Specification, and the convention that an application’s “main” interface and object path resemble its application identifier and bus name. To avoid situations that require special-case handling, it is recommended that new application identifiers consistently replace hyphens with underscores.

Like D-Bus interface names, application identifiers should start with the reversed DNS domain name of the author of the interface (in lower-case), and it is conventional for the rest of the application identifier to consist of words run together, with initial capital letters.

As with D-Bus interface names, if the author’s DNS domain name contains hyphen/minus characters they should be replaced by underscores, and if it contains leading digits they should be escaped by prepending an underscore. For example, if the owner of 7-zip.org used an application identifier for an archiving application, it might be named org._7_zip.Archiver.

application_id

a potential application identifier

Returns

true if application_id is valid

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

Returns the “default value” for a type. Read more

Formats the value using the given formatter. Read more

Feeds this value into the given Hasher. Read more

Feeds a slice of this type into the given Hasher. Read more

Override the virtual methods of this class for the given subclass and do other class initialization. Read more

Instance specific initialization. Read more

This method returns an Ordering between self and other. Read more

Compares and returns the maximum of two values. Read more

Compares and returns the minimum of two values. Read more

Restrict a value to a certain interval. Read more

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

This method returns an ordering between self and other values if one exists. Read more

This method tests less than (for self and other) and is used by the < operator. Read more

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more

This method tests greater than (for self and other) and is used by the > operator. Read more

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

Returns the type identifier of Self.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Upcasts an object to a superclass or interface T. Read more

Upcasts an object to a reference of its superclass or interface T. Read more

Tries to downcast to a subclass or interface implementor T. Read more

Tries to downcast to a reference of its subclass or interface implementor T. Read more

Tries to cast to an object of type T. This handles upcasting, downcasting and casting between interface and interface implementors. All checks are performed at runtime, while downcast and upcast will do many checks at compile-time already. Read more

Tries to cast to reference to an object of type T. This handles upcasting, downcasting and casting between interface and interface implementors. All checks are performed at runtime, while downcast and upcast will do many checks at compile-time already. Read more

Casts to T unconditionally. Read more

Casts to &T unconditionally. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

Returns true if the object is an instance of (can be cast to) T.

Returns the type of the object.

Returns the ObjectClass of the object. Read more

Returns the class of the object.

Returns the class of the object in the given type T. Read more

Returns the interface T of the object. Read more

Similar to Self::set_property but fails instead of panicking.

Sets the property property_name of the object to value value. Read more

Similar to Self::set_property but fails instead of panicking.

Sets the property property_name of the object to value value. Read more

Similar to Self::set_properties but fails instead of panicking.

Sets multiple properties of the object at once. Read more

Similar to Self::set_properties_from_value but fails instead of panicking.

Sets multiple properties of the object at once. Read more

Similar to Self::property but fails instead of panicking.

Gets the property property_name of the object and cast it to the type V. Read more

Similar to Self::property_value but fails instead of panicking.

Gets the property property_name of the object. Read more

Check if the object has a property property_name of the given type_. Read more

Get the type of the property property_name of this object. Read more

Get the ParamSpec of the property property_name of this object.

Return all ParamSpec of the properties of this object.

Freeze all property notifications until the return guard object is dropped. Read more

Set arbitrary data on this object with the given key. Read more

Return previously set arbitrary data of this object with the given key. Read more

Retrieve previously set arbitrary data of this object with the given key. Read more

Set arbitrary data on this object with the given key. Read more

Return previously set arbitrary data of this object with the given key. Read more

Retrieve previously set arbitrary data of this object with the given key. Read more

Block a given signal handler. Read more

Unblock a given signal handler.

Stop emission of the currently emitted signal.

Stop emission of the currently emitted signal by the (possibly detailed) signal name.

Similar to Self::connect but fails instead of panicking.

Connect to the signal signal_name on this object. Read more

Similar to Self::connect_id but fails instead of panicking.

Connect to the signal signal_id on this object. Read more

Similar to Self::connect_local but fails instead of panicking.

Connect to the signal signal_name on this object. Read more

Similar to Self::connect_local_id but fails instead of panicking.

Connect to the signal signal_id on this object. Read more

Similar to Self::connect_unsafe but fails instead of panicking.

Connect to the signal signal_name on this object. Read more

Similar to Self::connect_unsafe_id but fails instead of panicking.

Similar to Self::connect_closure but fails instead of panicking.

Connect a closure to the signal signal_name on this object. Read more

Similar to Self::connect_closure_id but fails instead of panicking.

Connect a closure to the signal signal_id on this object. Read more

Limits the lifetime of closure to the lifetime of the object. When the object’s reference count drops to zero, the closure will be invalidated. An invalidated closure will ignore any calls to Closure::invoke. Read more

Connect to the signal signal_id on this object. Read more

Similar to Self::emit but fails instead of panicking.

Emit signal by signal id. Read more

Similar to Self::emit_with_values but fails instead of panicking.

Same as Self::emit but takes Value for the arguments.

Similar to Self::emit_by_name but fails instead of panicking.

Emit signal by its name. Read more

Similar to Self::emit_by_name_with_values but fails instead of panicking.

Emit signal by its name. Read more

Similar to Self::emit_by_name_with_details but fails instead of panicking.

Emit signal by its name with details. Read more

Similar to Self::emit_by_name_with_details_and_values but fails instead of panicking.

Emit signal by its name with details. Read more

Similar to Self::emit_with_details but fails instead of panicking.

Emit signal by signal id with details. Read more

Similar to Self::emit_with_details_and_values but fails instead of panicking.

Emit signal by signal id with details. Read more

Disconnect a previously connected signal handler.

Connect to the notify signal of the object. Read more

Connect to the notify signal of the object. Read more

Connect to the notify signal of the object. Read more

Notify that the given property has changed its value. Read more

Notify that the given property has changed its value. Read more

Downgrade this object to a weak reference.

Bind property source_property on this object to the target_property on the target object. Read more

Returns the strong reference count of this object.

Ensures that the type has been registered with the type system.

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

Uses borrowed data to replace owned data, usually by cloning. Read more

Converts the given value to a String. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.