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|
"""
This module contains the base implementation of :class:`can.BusABC` as well
as a list of all available backends and some implemented
CyclicSendTasks.
"""
import importlib
import logging
from typing import Any, Iterable, List, Optional, Type, Union, cast
from . import util
from .bus import BusABC
from .exceptions import CanInterfaceNotImplementedError
from .interfaces import BACKENDS
from .typechecking import AutoDetectedConfig, Channel
log = logging.getLogger("can.interface")
log_autodetect = log.getChild("detect_available_configs")
def _get_class_for_interface(interface: str) -> Type[BusABC]:
"""
Returns the main bus class for the given interface.
:raises:
NotImplementedError if the interface is not known
:raises CanInterfaceNotImplementedError:
if there was a problem while importing the interface or the bus class within that
"""
# Find the correct backend
try:
module_name, class_name = BACKENDS[interface]
except KeyError:
raise NotImplementedError(
f"CAN interface '{interface}' not supported"
) from None
# Import the correct interface module
try:
module = importlib.import_module(module_name)
except Exception as e:
raise CanInterfaceNotImplementedError(
f"Cannot import module {module_name} for CAN interface '{interface}': {e}"
) from None
# Get the correct class
try:
bus_class = getattr(module, class_name)
except Exception as e:
raise CanInterfaceNotImplementedError(
f"Cannot import class {class_name} from module {module_name} for CAN interface "
f"'{interface}': {e}"
) from None
return cast(Type[BusABC], bus_class)
@util.deprecated_args_alias(
deprecation_start="4.2.0",
deprecation_end="5.0.0",
bustype="interface",
context="config_context",
)
def Bus( # noqa: N802
channel: Optional[Channel] = None,
interface: Optional[str] = None,
config_context: Optional[str] = None,
ignore_config: bool = False,
**kwargs: Any,
) -> BusABC:
"""Create a new bus instance with configuration loading.
Instantiates a CAN Bus of the given ``interface``, falls back to reading a
configuration file from default locations.
.. note::
Please note that while the arguments provided to this class take precedence
over any existing values from configuration, it is possible that other parameters
from the configuration may be added to the bus instantiation.
This could potentially have unintended consequences. To prevent this,
you may use the *ignore_config* parameter to ignore any existing configurations.
:param channel:
Channel identification. Expected type is backend dependent.
Set to ``None`` to let it be resolved automatically from the default
:ref:`configuration`.
:param interface:
See :ref:`interface names` for a list of supported interfaces.
Set to ``None`` to let it be resolved automatically from the default
:ref:`configuration`.
:param config_context:
Extra 'context', that is passed to config sources.
This can be used to select a section other than 'default' in the configuration file.
:param ignore_config:
If ``True``, only the given arguments will be used for the bus instantiation. Existing
configuration sources will be ignored.
:param kwargs:
``interface`` specific keyword arguments.
:raises ~can.exceptions.CanInterfaceNotImplementedError:
if the ``interface`` isn't recognized or cannot be loaded
:raises ~can.exceptions.CanInitializationError:
if the bus cannot be instantiated
:raises ValueError:
if the ``channel`` could not be determined
"""
# figure out the rest of the configuration; this might raise an error
if interface is not None:
kwargs["interface"] = interface
if channel is not None:
kwargs["channel"] = channel
if not ignore_config:
kwargs = util.load_config(config=kwargs, context=config_context)
# resolve the bus class to use for that interface
cls = _get_class_for_interface(kwargs["interface"])
# remove the "interface" key, so it doesn't get passed to the backend
del kwargs["interface"]
# make sure the bus can handle this config format
channel = kwargs.pop("channel", channel)
if channel is None:
# Use the default channel for the backend
bus = cls(**kwargs)
else:
bus = cls(channel, **kwargs)
return bus
def detect_available_configs(
interfaces: Union[None, str, Iterable[str]] = None
) -> List[AutoDetectedConfig]:
"""Detect all configurations/channels that the interfaces could
currently connect with.
This might be quite time-consuming.
Automated configuration detection may not be implemented by
every interface on every platform. This method will not raise
an error in that case, but with rather return an empty list
for that interface.
:param interfaces: either
- the name of an interface to be searched in as a string,
- an iterable of interface names to search in, or
- `None` to search in all known interfaces.
:rtype: list[dict]
:return: an iterable of dicts, each suitable for usage in
the constructor of :class:`can.BusABC`.
"""
# Figure out where to search
if interfaces is None:
interfaces = BACKENDS
elif isinstance(interfaces, str):
interfaces = (interfaces,)
# else it is supposed to be an iterable of strings
result = []
for interface in interfaces:
try:
bus_class = _get_class_for_interface(interface)
except CanInterfaceNotImplementedError:
log_autodetect.debug(
'interface "%s" cannot be loaded for detection of available configurations',
interface,
)
continue
# get available channels
try:
available = list(
bus_class._detect_available_configs() # pylint: disable=protected-access
)
except NotImplementedError:
log_autodetect.debug(
'interface "%s" does not support detection of available configurations',
interface,
)
else:
log_autodetect.debug(
'interface "%s" detected %i available configurations',
interface,
len(available),
)
# add the interface name to the configs if it is not already present
for config in available:
if "interface" not in config:
config["interface"] = interface
# append to result
result += available
return result
|
