idasit/dbus_fast/glib/proxy_object.py

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2024-12-14 14:55:37 +01:00
import xml.etree.ElementTree as ET
from typing import List, Union
from .. import introspection as intr
from ..constants import ErrorType
from ..errors import DBusError
from ..message import Message
from ..message_bus import BaseMessageBus
from ..proxy_object import BaseProxyInterface, BaseProxyObject
from ..signature import Variant
from ..unpack import unpack_variants as unpack
# glib is optional
try:
from gi.repository import GLib
except ImportError:
pass
class ProxyInterface(BaseProxyInterface):
"""A class representing a proxy to an interface exported on the bus by
another client for the GLib :class:`MessageBus <dbus_fast.glib.MessageBus>`
implementation.
This class is not meant to be constructed directly by the user. Use
:func:`ProxyObject.get_interface()
<dbus_fast.glib.ProxyObject.get_interface>` on a GLib proxy
object to get a proxy interface.
This class exposes methods to call DBus methods, listen to signals, and get
and set properties on the interface that are created dynamically based on
the introspection data passed to the proxy object that made this proxy
interface.
A *method call* takes this form:
.. code-block:: python3
def callback(error: Exception, result: list(Any)):
pass
interface.call_[METHOD](*args, callback)
result = interface.call_[METHOD]_sync(*args)
Where ``METHOD`` is the name of the method converted to snake case.
To call a method, provide ``*args`` that correspond to the *in args* of the
introspection method definition.
To *asynchronously* call a method, provide a callback that takes an error
as the first argument and a list as the second argument. If the call
completed successfully, ``error`` will be :class:`None`. If the service
returns an error, it will be a :class:`DBusError <dbus_fast.DBusError>`
with information about the error returned from the bus. The result will be
a list of values that correspond to the *out args* of the introspection
method definition.
To *synchronously* call a method, use the ``call_[METHOD]_sync()`` form.
The ``result`` corresponds to the *out arg* of the introspection method
definition. If the method has more than one otu arg, they are returned
within a :class:`list`.
To *listen to a signal* use this form:
.. code-block:: python3
interface.on_[SIGNAL](callback)
To *stop listening to a signal* use this form:
.. code-block:: python3
interface.off_[SIGNAL](callback)
Where ``SIGNAL`` is the name of the signal converted to snake case.
DBus signals are exposed with an event-callback interface. The provided
``callback`` will be called when the signal is emitted with arguments that
correspond to the *out args* of the interface signal definition.
To *get or set a property* use this form:
.. code-block:: python3
def get_callback(error: Exception, value: Any):
pass
def set_callback(error: Exception)
pass
interface.get_[PROPERTY](get_callback)
value: Any = interface.get_[PROPERTY]_sync()
interface.set_[PROPERTY](set_callback)
interface.set_[PROPERTY]_sync(value)
Where ``PROPERTY`` is the name of the property converted to snake case.
The ``value`` must correspond to the type of the property in the interface
definition.
To asynchronously get or set a property, provide a callback that takes an
:class:`Exception` as the first argument. If the call completed
successfully, ``error`` will be :class:`None`. If the service returns an
error, it will be a :class:`DBusError <dbus_fast.DBusError>` with
information about the error returned from the bus.
If the service returns an error for a synchronous DBus call, a
:class:`DBusError <dbus_fast.DBusError>` will be raised with information
about the error.
"""
def _add_method(self, intr_method):
in_len = len(intr_method.in_args)
out_len = len(intr_method.out_args)
def method_fn(*args, unpack_variants: bool = False):
if len(args) != in_len + 1:
raise TypeError(
f"method {intr_method.name} expects {in_len} arguments and a callback (got {len(args)} args)"
)
args = list(args)
# TODO type check: this callback takes two parameters
# (MessageBus.check_callback(cb))
callback = args.pop()
def call_notify(msg, err):
if err:
callback([], err)
return
try:
BaseProxyInterface._check_method_return(
msg, intr_method.out_signature
)
except DBusError as e:
err = e
if unpack_variants:
callback(unpack(msg.body), err)
else:
callback(msg.body, err)
self.bus.call(
Message(
destination=self.bus_name,
path=self.path,
interface=self.introspection.name,
member=intr_method.name,
signature=intr_method.in_signature,
body=list(args),
),
call_notify,
)
def method_fn_sync(*args, unpack_variants: bool = False):
main = GLib.MainLoop()
call_error = None
call_body = None
def callback(body, err):
nonlocal call_error
nonlocal call_body
call_error = err
call_body = body
main.quit()
method_fn(*args, callback)
main.run()
if call_error:
raise call_error
if not out_len:
return None
if unpack_variants:
call_body = unpack(call_body)
if out_len == 1:
return call_body[0]
return call_body
method_name = f"call_{BaseProxyInterface._to_snake_case(intr_method.name)}"
method_name_sync = f"{method_name}_sync"
setattr(self, method_name, method_fn)
setattr(self, method_name_sync, method_fn_sync)
def _add_property(self, intr_property):
def property_getter(callback, *, unpack_variants: bool = False):
def call_notify(msg, err):
if err:
callback(None, err)
return
try:
BaseProxyInterface._check_method_return(msg)
except Exception as e:
callback(None, e)
return
variant = msg.body[0]
if variant.signature != intr_property.signature:
err = DBusError(
ErrorType.CLIENT_ERROR,
'property returned unexpected signature "{variant.signature}"',
msg,
)
callback(None, err)
return
if unpack_variants:
callback(unpack(variant.value), None)
else:
callback(variant.value, None)
self.bus.call(
Message(
destination=self.bus_name,
path=self.path,
interface="org.freedesktop.DBus.Properties",
member="Get",
signature="ss",
body=[self.introspection.name, intr_property.name],
),
call_notify,
)
def property_getter_sync(*, unpack_variants: bool = False):
property_value = None
reply_error = None
main = GLib.MainLoop()
def callback(value, err):
nonlocal property_value
nonlocal reply_error
property_value = value
reply_error = err
main.quit()
property_getter(callback)
main.run()
if reply_error:
raise reply_error
if unpack_variants:
return unpack(property_value)
return property_value
def property_setter(value, callback):
def call_notify(msg, err):
if err:
callback(None, err)
return
try:
BaseProxyInterface._check_method_return(msg)
except Exception as e:
callback(None, e)
return
return callback(None, None)
variant = Variant(intr_property.signature, value)
self.bus.call(
Message(
destination=self.bus_name,
path=self.path,
interface="org.freedesktop.DBus.Properties",
member="Set",
signature="ssv",
body=[self.introspection.name, intr_property.name, variant],
),
call_notify,
)
def property_setter_sync(val):
reply_error = None
main = GLib.MainLoop()
def callback(value, err):
nonlocal reply_error
reply_error = err
main.quit()
property_setter(val, callback)
main.run()
if reply_error:
raise reply_error
return None
snake_case = super()._to_snake_case(intr_property.name)
setattr(self, f"get_{snake_case}", property_getter)
setattr(self, f"get_{snake_case}_sync", property_getter_sync)
setattr(self, f"set_{snake_case}", property_setter)
setattr(self, f"set_{snake_case}_sync", property_setter_sync)
class ProxyObject(BaseProxyObject):
"""The proxy object implementation for the asyncio :class:`MessageBus <dbus_fast.aio.MessageBus>`.
For more information, see the :class:`BaseProxyObject <dbus_fast.proxy_object.BaseProxyObject>`.
"""
def __init__(
self,
bus_name: str,
path: str,
introspection: Union[intr.Node, str, ET.Element],
bus: BaseMessageBus,
):
super().__init__(bus_name, path, introspection, bus, ProxyInterface)
def get_interface(self, name: str) -> ProxyInterface:
return super().get_interface(name)
def get_children(self) -> List["ProxyObject"]:
return super().get_children()