Source code for qcodes.instrument.channel

""" Base class for the channel of an instrument """
import sys
from typing import (
    Any,
    Callable,
    Dict,
    Iterable,
    Iterator,
    List,
    MutableSequence,
    Optional,
    Sequence,
    Tuple,
    Type,
    TypeVar,
    Union,
    cast,
    overload,
)

from qcodes.parameters import (
    ArrayParameter,
    MultiChannelInstrumentParameter,
    MultiParameter,
    Parameter,
)
from qcodes.parameters.multi_channel_instrument_parameter import InstrumentModuleType
from qcodes.utils import full_class
from qcodes.validators import Validator

from ..utils.metadata import Metadatable
from .instrument import Instrument
from .instrument_base import InstrumentBase


[docs]class InstrumentModule(InstrumentBase): """ Base class for a module in an instrument. This could be in the form of a channel (e.g. something that the instrument has multiple instances of) or another logical grouping of parameters that you wish to group together separate from the rest of the instrument. Args: parent: The instrument to which this module should be attached. name: The name of this module. """ def __init__(self, parent: InstrumentBase, name: str, **kwargs: Any) -> None: # need to specify parent before `super().__init__` so that the right # `full_name` is available in that scope. `full_name` is used for # registering the filter for the log messages. It is composed by # iteratively concatenating the full names of the parent instruments # scope of `Base` self._parent = parent super().__init__(name=name, **kwargs)
[docs] def __repr__(self) -> str: """Custom repr to give parent information""" return ( f"<{type(self).__name__}: {self.name} of " f"{type(self._parent).__name__}: {self._parent.name}>" )
# Pass any commands to read or write from the instrument up to the parent
[docs] def write(self, cmd: str) -> None: return self._parent.write(cmd)
[docs] def write_raw(self, cmd: str) -> None: return self._parent.write_raw(cmd)
[docs] def ask(self, cmd: str) -> str: return self._parent.ask(cmd)
[docs] def ask_raw(self, cmd: str) -> str: return self._parent.ask_raw(cmd)
@property def parent(self) -> InstrumentBase: return self._parent @property def root_instrument(self) -> InstrumentBase: return self._parent.root_instrument @property def name_parts(self) -> List[str]: name_parts = list(self._parent.name_parts) name_parts.append(self.short_name) return name_parts
[docs]class InstrumentChannel(InstrumentModule): pass
T = TypeVar("T", bound="ChannelTuple")
[docs]class ChannelTuple(Metadatable, Sequence[InstrumentModuleType]): """ Container for channelized parameters that allows for sweeps over all channels, as well as addressing of individual channels. This behaves like a python tuple i.e. it implements the :class:`collections.abc.Sequence` interface. Args: parent: The instrument to which this ChannelTuple should be attached. name: The name of the ChannelTuple. chan_type: The type of channel contained within this tuple. chan_list: An optional iterable of channels of type ``chan_type``. snapshotable: Optionally disables taking of snapshots for a given ChannelTuple. This is used when objects stored inside a ChannelTuple are accessible in multiple ways and should not be repeated in an instrument snapshot. multichan_paramclass: The class of the object to be returned by the :meth:`__getattr__` method of :class:`ChannelTuple`. Should be a subclass of :class:`.MultiChannelInstrumentParameter`. Defaults to :class:`.MultiChannelInstrumentParameter` if None. Raises: ValueError: If ``chan_type`` is not a subclass of :class:`InstrumentChannel` ValueError: If ``multichan_paramclass`` is not a subclass of :class:`.MultiChannelInstrumentParameter` (note that a class is a subclass of itself). """ def __init__( self, parent: InstrumentBase, name: str, chan_type: Type[InstrumentModuleType], chan_list: Optional[Sequence[InstrumentModuleType]] = None, snapshotable: bool = True, multichan_paramclass: Optional[Type[MultiChannelInstrumentParameter]] = None, ): if multichan_paramclass is None: multichan_paramclass = MultiChannelInstrumentParameter super().__init__() self._parent = parent self._name = name if not isinstance(chan_type, type) or not issubclass( chan_type, InstrumentChannel ): raise ValueError( "ChannelTuple can only hold instances of type InstrumentChannel" ) if not isinstance(multichan_paramclass, type) or not issubclass( multichan_paramclass, MultiChannelInstrumentParameter ): raise ValueError( "multichan_paramclass must be a (subclass of) " "MultiChannelInstrumentParameter" ) self._chan_type = chan_type self._snapshotable = snapshotable self._paramclass = multichan_paramclass self._channel_mapping: Dict[str, InstrumentModuleType] = {} # provide lookup of channels by name # If a list of channels is not provided, define a list to store # channels. This will eventually become a locked tuple. self._channels: List[InstrumentModuleType] if chan_list is None: self._channels = [] else: self._channels = list(chan_list) self._channel_mapping = {channel.short_name: channel for channel in self._channels} if not all(isinstance(chan, chan_type) for chan in self._channels): raise TypeError( f"All items in this ChannelTuple must be of " f"type {chan_type.__name__}." ) @overload def __getitem__(self, i: int) -> "InstrumentModuleType": ... @overload def __getitem__(self: T, i: Union[slice, Tuple[int, ...]]) -> T: ...
[docs] def __getitem__( self: T, i: Union[int, slice, Tuple[int, ...]] ) -> Union[InstrumentModuleType, T]: """ Return either a single channel, or a new :class:`ChannelTuple` containing only the specified channels Args: i: Either a single channel index or a slice of channels to get """ if isinstance(i, slice): return type(self)( self._parent, self._name, self._chan_type, self._channels[i], multichan_paramclass=self._paramclass, snapshotable=self._snapshotable, ) elif isinstance(i, tuple): return type(self)( self._parent, self._name, self._chan_type, [self._channels[j] for j in i], multichan_paramclass=self._paramclass, snapshotable=self._snapshotable, ) return self._channels[i]
def __iter__(self) -> Iterator["InstrumentModuleType"]: return iter(self._channels) def __reversed__(self) -> Iterator["InstrumentModuleType"]: return reversed(self._channels) def __len__(self) -> int: return len(self._channels) def __contains__(self, item: object) -> bool: return item in self._channels def __repr__(self) -> str: return ( f"ChannelTuple({self._parent!r}, " f"{self._chan_type.__name__}, {self._channels!r})" )
[docs] def __add__(self: T, other: "ChannelTuple") -> T: """ Return a new ChannelTuple containing the channels from both :class:`ChannelTuple` self and r. Both ChannelTuple must hold the same type and have the same parent. Args: other: Right argument to add. """ if not isinstance(self, ChannelTuple) or not isinstance(other, ChannelTuple): raise TypeError( f"Can't add objects of type" f" {type(self).__name__} and {type(other).__name__} together" ) if self._chan_type != other._chan_type: raise TypeError( f"Both l and r arguments to add must contain " f"channels of the same type." f" Adding channels of type " f"{self._chan_type.__name__} and {other._chan_type.__name__}." ) if self._parent != other._parent: raise ValueError("Can only add channels from the same parent " "together.") return type(self)( self._parent, self._name, self._chan_type, list(self._channels) + list(other._channels), snapshotable=self._snapshotable, )
[docs] def index( self, obj: InstrumentModuleType, start: int = 0, stop: int = sys.maxsize ) -> int: """ Return the index of the given object Args: obj: The object to find in the channel list. start: Index to start searching from. stop: Index to stop searching at. """ return self._channels.index(obj, start, stop)
[docs] def count(self, obj: InstrumentModuleType) -> int: """Returns number of instances of the given object in the list Args: obj: The object to find in the ChannelTuple. """ return self._channels.count(obj)
[docs] def get_channel_by_name(self: T, *names: str) -> Union[InstrumentModuleType, T]: """ Get a channel by name, or a ChannelTuple if multiple names are given. Args: *names: channel names """ if len(names) == 0: raise Exception("one or more names must be given") if len(names) == 1: return self._channel_mapping[names[0]] selected_channels = tuple(self._channel_mapping[name] for name in names) return type(self)( self._parent, self._name, self._chan_type, selected_channels, self._snapshotable, self._paramclass, )
[docs] def get_validator(self) -> "ChannelTupleValidator": """ Returns a validator that checks that the returned object is a channel in this ChannelTuple """ return ChannelTupleValidator(self)
[docs] def snapshot_base(self, update: Optional[bool] = True, params_to_skip_update: Optional[Sequence[str]] = None ) -> Dict[Any, Any]: """ State of the instrument as a JSON-compatible dict (everything that the custom JSON encoder class :class:`.NumpyJSONEncoder` supports). Args: update: If True, update the state by querying the instrument. If None only update if the state is known to be invalid. If False, just use the latest values in memory and never update. params_to_skip_update: List of parameter names that will be skipped in update even if update is True. This is useful if you have parameters that are slow to update but can be updated in a different way (as in the qdac). If you want to skip the update of certain parameters in all snapshots, use the ``snapshot_get`` attribute of those parameters instead. Returns: dict: base snapshot """ if self._snapshotable: snap = {'channels': {chan.name: chan.snapshot(update=update) for chan in self._channels}, 'snapshotable': self._snapshotable, '__class__': full_class(self), } else: snap = {'snapshotable': self._snapshotable, '__class__': full_class(self), } return snap
[docs] def __getattr__( self, name: str ) -> Union[ MultiChannelInstrumentParameter, Callable[..., None], InstrumentModuleType ]: """ Look up an attribute by name. If this is the name of a parameter or a function on the channel type contained in this container return a multi-channel function or parameter that can be used to get or set all items in a channel list simultaneously. If this is the name of a channel, return that channel. Args: name: The name of the parameter, function or channel that we want to operate on. """ # Check if this is a valid parameter if len(self) > 0: if name in self._channels[0].parameters: param = self._construct_multiparam(name) return param # Check if this is a valid function if name in self._channels[0].functions: # We want to return a reference to a function that would call the # function for each of the channels in turn. def multi_func(*args: Any) -> None: for chan in self._channels: chan.functions[name](*args) return multi_func try: return self._channel_mapping[name] except KeyError: pass raise AttributeError( f"'{self.__class__.__name__}' object has no attribute '{name}'" )
def _construct_multiparam(self, name: str) -> MultiChannelInstrumentParameter: setpoints = None setpoint_names = None setpoint_labels = None setpoint_units = None # We need to construct a MultiParameter object to get each of the # values our of each parameter in our list, we don't currently try # to construct a multiparameter from a list of multi parameters if isinstance(self._channels[0].parameters[name], MultiParameter): raise NotImplementedError( "Slicing is currently not " "supported for MultiParameters" ) parameters = cast( List[Union[Parameter, ArrayParameter]], [chan.parameters[name] for chan in self._channels], ) names = tuple(f"{chan.name}_{name}" for chan in self._channels) labels = tuple(parameter.label for parameter in parameters) units = tuple(parameter.unit for parameter in parameters) if isinstance(parameters[0], ArrayParameter): arrayparameters = cast(List[ArrayParameter], parameters) shapes = tuple(parameter.shape for parameter in arrayparameters) if arrayparameters[0].setpoints: setpoints = tuple(parameter.setpoints for parameter in arrayparameters) if arrayparameters[0].setpoint_names: setpoint_names = tuple( parameter.setpoint_names for parameter in arrayparameters ) if arrayparameters[0].setpoint_labels: setpoint_labels = tuple( parameter.setpoint_labels for parameter in arrayparameters ) if arrayparameters[0].setpoint_units: setpoint_units = tuple( parameter.setpoint_units for parameter in arrayparameters ) else: shapes = tuple(() for _ in self._channels) param = self._paramclass( self._channels, param_name=name, name=f"Multi_{name}", names=names, shapes=shapes, instrument=self._parent, labels=labels, units=units, setpoints=setpoints, setpoint_names=setpoint_names, setpoint_units=setpoint_units, setpoint_labels=setpoint_labels, bind_to_instrument=False, ) return param def __dir__(self) -> List[Any]: names = list(super().__dir__()) if self._channels: names += list(self._channels[0].parameters.keys()) names += list(self._channels[0].functions.keys()) names += [channel.short_name for channel in self._channels] return sorted(set(names))
[docs] def print_readable_snapshot(self, update: bool = False, max_chars: int = 80) -> None: if self._snapshotable: for channel in self._channels: channel.print_readable_snapshot(update=update, max_chars=max_chars)
[docs] def invalidate_cache(self) -> None: """ Invalidate the cache of all parameters on the ChannelTuple. """ for chan in self._channels: chan.invalidate_cache()
# we ignore a mypy error here since the __getitem__ signature above # taking a tuple is not compatible with MutableSequence # for some reason this does not happen with Sequence
[docs]class ChannelList(ChannelTuple, MutableSequence[InstrumentModuleType]): # type: ignore[misc] """ Mutable Container for channelized parameters that allows for sweeps over all channels, as well as addressing of individual channels. This behaves like a python list i.e. it implements the :class:`collections.abc.MutableSequence` interface. Note it may be useful to use the mutable ChannelList while constructing it. E.g. adding channels as they are created, but in most use cases it is recommended to convert this to a :class:`ChannelTuple` before adding it to an instrument. This can be done using the :meth:`to_channel_tuple` method. Args: parent: The instrument to which this :class:`ChannelList` should be attached. name: The name of the :class:`ChannelList`. chan_type: The type of channel contained within this list. chan_list: An optional iterable of channels of type ``chan_type``. This will create a list and immediately lock the :class:`ChannelList`. snapshotable: Optionally disables taking of snapshots for a given ChannelList. This is used when objects stored inside a ChannelList are accessible in multiple ways and should not be repeated in an instrument snapshot. multichan_paramclass: The class of the object to be returned by the :meth:`__getattr__` method of :class:`ChannelList`. Should be a subclass of :class:`.MultiChannelInstrumentParameter`. Defaults to :class:`.MultiChannelInstrumentParameter` if None. Raises: ValueError: If ``chan_type`` is not a subclass of :class:`InstrumentChannel` ValueError: If ``multichan_paramclass`` is not a subclass of :class:`.MultiChannelInstrumentParameter` (note that a class is a subclass of itself). """ def __init__( self, parent: InstrumentBase, name: str, chan_type: Type[InstrumentModuleType], chan_list: Optional[Sequence[InstrumentModuleType]] = None, snapshotable: bool = True, multichan_paramclass: Optional[Type[MultiChannelInstrumentParameter]] = None, ): if multichan_paramclass is None: multichan_paramclass = MultiChannelInstrumentParameter super().__init__( parent, name, chan_type, chan_list, snapshotable, multichan_paramclass ) if len(self._channels) > 0: self._locked = True else: self._locked = False @overload def __delitem__(self, key: int) -> None: ... @overload def __delitem__(self, key: slice) -> None: ... def __delitem__(self, key: Union[int, slice]) -> None: if self._locked: raise AttributeError("Cannot delete from a locked channel list") self._channels.__delitem__(key) self._channel_mapping = { channel.short_name: channel for channel in self._channels } @overload def __setitem__(self, index: int, value: InstrumentModuleType) -> None: ... @overload def __setitem__(self, index: slice, value: Iterable[InstrumentModuleType]) -> None: ... def __setitem__( self, index: Union[int, slice], value: Union[InstrumentModuleType, Iterable[InstrumentModuleType]], ) -> None: if self._locked: raise AttributeError("Cannot set item in a locked channel list") # update mapping # asserts added to work around https://github.com/python/mypy/issues/7858 if isinstance(index, int): assert isinstance(value, InstrumentChannel) self._channels[index] = value else: assert not isinstance(value, InstrumentChannel) self._channels[index] = value self._channel_mapping = { channel.short_name: channel for channel in self._channels }
[docs] def append(self, obj: InstrumentModuleType) -> None: """ Append a Channel to this list. Requires that the ChannelList is not locked and that the channel is of the same type as the ones in the list. Args: obj: New channel to add to the list. """ if self._locked: raise AttributeError("Cannot append to a locked channel list") if not isinstance(obj, self._chan_type): raise TypeError( f"All items in a channel list must be of the same " f"type. Adding {type(obj).__name__} to a " f"list of {self._chan_type.__name__}." ) self._channel_mapping[obj.short_name] = obj self._channels.append(obj)
[docs] def clear(self) -> None: """ Clear all items from the ChannelList. """ if self._locked: raise AttributeError("Cannot clear a locked ChannelList") # when not locked the _channels seq is a list self._channels.clear() self._channel_mapping.clear()
[docs] def remove(self, obj: InstrumentModuleType) -> None: """ Removes obj from ChannelList if not locked. Args: obj: Channel to remove from the list. """ if self._locked: raise AttributeError("Cannot remove from a locked channel list") else: self._channels.remove(obj) self._channel_mapping.pop(obj.short_name)
[docs] def extend(self, objects: Iterable[InstrumentModuleType]) -> None: """ Insert an iterable of objects into the list of channels. Args: objects: A list of objects to add into the :class:`ChannelList`. """ # objects may be a generator but we need to iterate over it twice # below so copy it into a tuple just in case. if self._locked: raise AttributeError("Cannot extend a locked channel list") objects_tuple = tuple(objects) if not all(isinstance(obj, self._chan_type) for obj in objects_tuple): raise TypeError("All items in a channel list must be of the same type.") self._channels.extend(objects_tuple) self._channel_mapping.update({obj.short_name: obj for obj in objects_tuple})
[docs] def insert(self, index: int, obj: InstrumentModuleType) -> None: """ Insert an object into the ChannelList at a specific index. Args: index: Index to insert object. obj: Object of type chan_type to insert. """ if self._locked: raise AttributeError("Cannot insert into a locked channel list") if not isinstance(obj, self._chan_type): raise TypeError( f"All items in a channel list must be of the same " f"type. Adding {type(obj).__name__} to a list of {self._chan_type.__name__}." ) self._channels.insert(index, obj) self._channel_mapping[obj.short_name] = obj
[docs] def get_validator(self) -> "ChannelTupleValidator": """ Returns a validator that checks that the returned object is a channel in this ChannelList. Raises: AttributeError: If the ChannelList is not locked. """ if not self._locked: raise AttributeError( "Cannot create a validator for an unlocked ChannelList" ) return super().get_validator()
[docs] def lock(self) -> None: """ Lock the channel list. Once this is done, the ChannelList is locked and any future changes to the list are prevented. Note this is not recommended and may be deprecated in the future. Use ``to_channel_tuple`` to convert this into a tuple instead. """ if self._locked: return self._locked = True
[docs] def to_channel_tuple(self) -> ChannelTuple: """ Returns a ChannelTuple build from this ChannelList containing the same channels but without the ability to be modified. """ return ChannelTuple( self._parent, self._name, self._chan_type, self._channels, multichan_paramclass=self._paramclass, snapshotable=self._snapshotable, )
def __repr__(self) -> str: return ( f"ChannelList({self._parent!r}, " f"{self._chan_type.__name__}, {self._channels!r})" )
class ChannelTupleValidator(Validator[InstrumentChannel]): """ A validator that checks that the returned object is a member of the ChannelTuple with which the validator was constructed. This class will not normally be created directly, but created from a channel list using the ``ChannelTuple.get_validator`` method. Args: channel_list: the ChannelTuple that should be checked against. The channel list must be locked and populated before it can be used to construct a validator. """ def __init__(self, channel_list: ChannelTuple) -> None: # Save the base parameter list if not isinstance(channel_list, ChannelTuple): raise ValueError( "channel_list must be a ChannelTuple " "object containing the " "channels that should be validated" ) if isinstance(channel_list, ChannelList) and not channel_list._locked: raise AttributeError( "channel_list must be locked before it can " "be used to create a validator" ) self._channel_list = channel_list def validate(self, value: InstrumentChannel, context: str = '') -> None: """ Checks to see that value is a member of the ChannelTuple referenced by this validator Args: value: the value to be checked against the reference channel list. context: the context of the call, used as part of the exception raised. """ if value not in self._channel_list: raise ValueError( f"{repr(value)} is not part of the expected channel list; {context}" ) class ChannelListValidator(ChannelTupleValidator): """Alias for backwards compatibility. Do not use""" pass class AutoLoadableInstrumentChannel(InstrumentChannel): """ This subclass provides extensions to auto-load channels from instruments and adds methods to create and delete channels when possible. Please note that `channel` in this context does not necessarily mean a physical instrument channel, but rather an instrument sub-module. For some instruments, these sub-modules can be created and deleted at will. """ @classmethod def load_from_instrument( cls, parent: Instrument, channel_list: Optional['AutoLoadableChannelList'] = None, **kwargs: Any ) -> List['AutoLoadableInstrumentChannel']: """ Load channels that already exist on the instrument Args: parent: The instrument through which the instrument channel is accessible channel_list: The channel list this channel is a part of **kwargs: Keyword arguments needed to create the channels Returns: List of instrument channel instances created for channels that already exist on the instrument """ obj_list = [] for new_kwargs in cls._discover_from_instrument(parent, **kwargs): obj = cls( parent, existence=True, channel_list=channel_list, **new_kwargs ) obj_list.append(obj) return obj_list @classmethod def _discover_from_instrument( cls, parent: Instrument, **kwargs: Any) -> List[Dict[Any, Any]]: """ Discover channels on the instrument and return a list kwargs to create these channels in memory Args: parent: The instrument through which the instrument channel is accessible **kwargs: Keyword arguments needed to discover the channels Returns: List of keyword arguments for channel instance initialization for each channel that already exists on the physical instrument """ raise NotImplementedError( "Please subclass and implement this method in the subclass") @classmethod def new_instance( cls, parent: Instrument, create_on_instrument: bool = True, channel_list: Optional['AutoLoadableChannelList'] = None, **kwargs: Any ) -> 'AutoLoadableInstrumentChannel': """ Create a new instance of the channel on the instrument: This involves finding initialization arguments which will create a channel with a unique name and create the channel on the instrument. Args: parent: The instrument through which the instrument channel is accessible create_on_instrument: When True, the channel is immediately created on the instrument channel_list: The channel list this channel is going to belong to **kwargs: Keyword arguments needed to create a new instance. """ new_kwargs = cls._get_new_instance_kwargs(parent=parent, **kwargs) try: new_instance = cls(parent, channel_list=channel_list, **new_kwargs) except TypeError as err: # The 'new_kwargs' dict is malformed. Investigate more precisely # why and give the user a more helpful hint how this can be # solved. if "name" not in new_kwargs: raise TypeError( "A 'name' argument should be supplied by the " "'_get_new_instance_kwargs' method" ) from err if "parent" in new_kwargs: raise TypeError( "A 'parent' argument should *not* be supplied by the " "'_get_new_instance_kwargs' method" ) from err # Something else has gone wrong. Probably, not all mandatory keyword # arguments are supplied raise TypeError( "Probably, the '_get_new_instance_kwargs' method does not " "return all of the required keyword arguments") from err if create_on_instrument: new_instance.create() return new_instance @classmethod def _get_new_instance_kwargs(cls, parent: Optional[Instrument] = None, **kwargs: Any) -> Dict[Any, Any]: """ Returns a dictionary which is used as keyword args when instantiating a channel Args: parent: The instrument the new channel will belong to. Not all instruments need this so it is an optional argument **kwargs: Additional arguments which are needed to instantiate a channel can be given directly by the calling function. Returns: A keyword argument dictionary with at least a ``name`` key which is unique on the instrument. The parent instrument is passed as an argument in this function so we can query if the generated name is indeed unique. Notes: The init arguments ``parent`` and ``channel_list`` are automatically added by the ``new_instance`` method and should not be added in the kwarg dictionary returned here. Additionally, the argument ``existence`` either needs to be omitted or be False. """ raise NotImplementedError( "Please subclass and implement this method in the subclass") def __init__( self, parent: Union[Instrument, 'InstrumentChannel'], name: str, exists_on_instrument: bool = False, channel_list: Optional['AutoLoadableChannelList'] = None, **kwargs: Any): """ Instantiate a channel object. Note that this is not the same as actually creating the channel on the instrument. Parameters defined on this channels will not be able to query/write to the instrument until it has been created on the instrument Args: parent: The instrument through which the instrument channel is accessible name: channel name exists_on_instrument: True if the channel exists on the instrument channel_list: Reference to the list that this channel is a member of; this is used when deleting the channel so that it can remove itself from the list """ super().__init__(parent, name=name, **kwargs) self._exists_on_instrument = exists_on_instrument self._channel_list = channel_list def create(self) -> None: """Create the channel on the instrument""" if self._exists_on_instrument: raise RuntimeError("Channel already exists on instrument") self._create() self._exists_on_instrument = True def _create(self) -> None: """ (SCPI) commands needed to create the channel. Note that we need to use ``self.root_instrument.write`` to send commands, because ``self.write`` will cause ``_assert_existence`` to raise a runtime error. """ raise NotImplementedError("Please subclass") def remove(self) -> None: """ Delete the channel from the instrument and remove from channel list """ self._assert_existence() self._remove() if self._channel_list is not None and self in self._channel_list: self._channel_list.remove(self) self._exists_on_instrument = False def _remove(self) -> None: """ (SCPI) commands needed to delete the channel from the instrument """ raise NotImplementedError("Please subclass") def _assert_existence(self) -> None: if not self._exists_on_instrument: raise RuntimeError( "Object does not exist (anymore) on the instrument") def write(self, cmd: str) -> None: """ Write to the instrument only if the channel is present on the instrument """ self._assert_existence() return super().write(cmd) def ask(self, cmd: str) -> str: """ Ask the instrument only if the channel is present on the instrument """ self._assert_existence() return super().ask(cmd) @property def exists_on_instrument(self) -> bool: return self._exists_on_instrument class AutoLoadableChannelList(ChannelList): """ Extends the QCoDeS :class:`ChannelList` class to add the following features: - Automatically create channel objects on initialization - Make a ``add`` method to create channel objects Args: parent: the instrument to which this channel should be attached name: the name of the channel list chan_type: the type of channel contained within this list chan_list: An optional iterable of channels of type chan_type. This will create a list and immediately lock the :class:`ChannelList`. snapshotable: Optionally disables taking of snapshots for a given channel list. This is used when objects stored inside a channel list are accessible in multiple ways and should not be repeated in an instrument snapshot. multichan_paramclass: The class of the object to be returned by the :class:`ChannelList` ``__getattr__`` method. Should be a subclass of :class:`MultiChannelInstrumentParameter`. **kwargs: Keyword arguments to be passed to the ``load_from_instrument`` method of the channel class. Note that the kwargs are *NOT* passed to the ``__init__`` of the super class. Raises: ValueError: If :class:`chan_type` is not a subclass of :class:`InstrumentChannel` ValueError: If ``multichan_paramclass`` is not a subclass of :class:`MultiChannelInstrumentParameter` (note that a class is a subclass of itself). """ def __init__( self, parent: Instrument, name: str, chan_type: type, chan_list: Optional[Sequence['AutoLoadableInstrumentChannel']] = None, snapshotable: bool = True, multichan_paramclass: type = MultiChannelInstrumentParameter, **kwargs: Any ) -> None: super().__init__( parent, name, chan_type, chan_list, snapshotable, multichan_paramclass ) new_channels = self._chan_type.load_from_instrument( # type: ignore[attr-defined] self._parent, channel_list=self, **kwargs) self.extend(new_channels) def add(self, **kwargs: Any) -> 'AutoLoadableInstrumentChannel': """ Add a channel to the list Args: kwargs: Keyword arguments passed to the ``new_instance`` method of the channel class Returns: Newly created instance of the channel class """ new_channel = self._chan_type.new_instance( # type: ignore[attr-defined] self._parent, create_on_instrument=True, channel_list=self, **kwargs ) self.append(new_channel) return new_channel