Initable

Added in version 2.22.

class Initable(*args, **kwargs)

Implementations: CharsetConverter, DBusConnection, DBusObjectManagerClient, DBusProxy, DBusServer, DebugControllerDBus, InetAddressMask, Socket, Subprocess

GInitable is implemented by objects that can fail during initialization. If an object implements this interface then it must be initialized as the first thing after construction, either via init or init_async (the latter is only available if it also implements AsyncInitable).

If the object is not initialized, or initialization returns with an error, then all operations on the object except :func:`~gi.repository.GObject.GObject.Object.ref` and :func:`~gi.repository.GObject.GObject.Object.unref` are considered to be invalid, and have undefined behaviour. They will often fail with critical or warning, but this must not be relied on.

Users of objects implementing this are not intended to use the interface method directly, instead it will be used automatically in various ways. For C applications you generally just call new directly, or indirectly via a foo_thing_new() wrapper. This will call init under the cover, returning NULL and setting a GError on failure (at which point the instance is unreferenced).

For bindings in languages where the native constructor supports exceptions the binding could check for objects implementing GInitable during normal construction and automatically initialize them, throwing an exception on failure.

Methods

class Initable

init(cancellable: Cancellable | None = None) → bool

Initializes the object implementing the interface.

This method is intended for language bindings. If writing in C, new() should typically be used instead.

The object must be initialized before any real use after initial construction, either with this function or init_async().

Implementations may also support cancellation. If cancellable is not None, then initialization can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error CANCELLED will be returned. If cancellable is not None and the object doesn’t support cancellable initialization the error NOT_SUPPORTED will be returned.

If the object is not initialized, or initialization returns with an error, then all operations on the object except ref() and unref() are considered to be invalid, and have undefined behaviour. See the [introduction][ginitable] for more details.

Callers should not assume that a class which implements Initable can be initialized multiple times, unless the class explicitly documents itself as supporting this. Generally, a class’ implementation of init() can assume (and assert) that it will only be called once. Previously, this documentation recommended all Initable implementations should be idempotent; that recommendation was relaxed in GLib 2.54.

If a class explicitly supports being initialized multiple times, it is recommended that the method is idempotent: multiple calls with the same arguments should return the same results. Only the first call initializes the object; further calls return the result of the first call.

One reason why a class might need to support idempotent initialization is if it is designed to be used via the singleton pattern, with a ObjectClass.constructor that sometimes returns an existing instance. In this pattern, a caller would expect to be able to call init() on the result of new(), regardless of whether it is in fact a new instance.

Added in version 2.22.

Parameters:

cancellable – optional Cancellable object, None to ignore.

newv(object_type: type, parameters: Sequence[Parameter], cancellable: Cancellable | None = None) → Object

Helper function for constructing Initable object. This is similar to newv() but also initializes the object and returns None, setting an error on failure.

Added in version 2.22.

Deprecated since version 2.54: Use new_with_properties() and init() instead. See Parameter for more information.

Parameters:

• object_type – a Type supporting Initable.

• parameters – the parameters to use to construct the object

• cancellable – optional Cancellable object, None to ignore.

Virtual Methods

class Initable

do_init(cancellable: Cancellable | None = None) → bool

Initializes the object implementing the interface.

This method is intended for language bindings. If writing in C, new() should typically be used instead.

The object must be initialized before any real use after initial construction, either with this function or init_async().

Implementations may also support cancellation. If cancellable is not None, then initialization can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error CANCELLED will be returned. If cancellable is not None and the object doesn’t support cancellable initialization the error NOT_SUPPORTED will be returned.

If the object is not initialized, or initialization returns with an error, then all operations on the object except ref() and unref() are considered to be invalid, and have undefined behaviour. See the [introduction][ginitable] for more details.

Callers should not assume that a class which implements Initable can be initialized multiple times, unless the class explicitly documents itself as supporting this. Generally, a class’ implementation of init() can assume (and assert) that it will only be called once. Previously, this documentation recommended all Initable implementations should be idempotent; that recommendation was relaxed in GLib 2.54.

If a class explicitly supports being initialized multiple times, it is recommended that the method is idempotent: multiple calls with the same arguments should return the same results. Only the first call initializes the object; further calls return the result of the first call.

One reason why a class might need to support idempotent initialization is if it is designed to be used via the singleton pattern, with a ObjectClass.constructor that sometimes returns an existing instance. In this pattern, a caller would expect to be able to call init() on the result of new(), regardless of whether it is in fact a new instance.

Added in version 2.22.

Parameters:

cancellable – optional Cancellable object, None to ignore.