Initializes the object implementing the interface. This must be
done before any real use of the object after initial construction.
Implementations may also support cancellation. If cancellable is not NULL,
then initialization can be cancelled by triggering the cancellable object
from another thread. If the operation was cancelled, the error
G_IO_ERROR_CANCELLED will be returned. If cancellable is not NULL and
the object doesn't support cancellable initialization the error
G_IO_ERROR_NOT_SUPPORTED will be returned.
If this function is not called, or returns with an error then all
operations on the object should fail, generally returning the
error G_IO_ERROR_NOT_INITIALIZED.
Implementations of this method must be idempotent, i.e. multiple calls
to this function with the same argument should return the same results.
Only the first call initializes the object, further calls return the result
of the first call. This is so that its safe to implement the singleton
pattern in the GObject constructor function.
return FALSE and set error appropriately if present.

Parameters:

Gio.Cancellable cancellable

optional GCancellable object, NULL to ignore.

Returns:

gboolean TRUE if successful. If an error has occurred, this function will