Merge pull request #7486 from jenshnielsen/channel_type_safe

More type safe ways of gettting channel attributes

Author: jenshnielsen

docs/changes/newsfragments/7486.breaking

@@ -0,0 +1,4 @@
+``ChannelTuple/ChannelList.get_channel_by_name`` support for getting more than one channel has been deprecated. To get more than one channel use ``get_channels_by_name``.
+``get_channels_by_name`` is guaranteed to always return an instance of the class it was called on independently of the number of channels supplied. In the future
+``get_channel_by_name`` will be updated to ensure that it always returns a single channel. The Exception raised when
+no argument is given to ``get_channel_by_name`` has changed from ``Exception`` to ``TypeError`` in line with how functions behave when an argument is missing.

src/qcodes/instrument/channel.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import sys
+import warnings
 from collections.abc import Callable, Iterable, Iterator, MutableSequence, Sequence
 from typing import TYPE_CHECKING, Any, TypeVar, cast, overload
 
@@ -14,7 +15,7 @@
     Parameter,
 )
 from qcodes.parameters.multi_channel_instrument_parameter import InstrumentModuleType
-from qcodes.utils import full_class
+from qcodes.utils import QCoDeSDeprecationWarning, full_class
 from qcodes.validators import Validator
 
 from .instrument_base import InstrumentBase
@@ -338,6 +339,26 @@ def count(  #  pyright: ignore[reportIncompatibleMethodOverride]
         """
         return self._channels.count(obj)
 
+    def get_channels_by_name(self: Self, *names: str) -> Self:
+        """
+        Get a a ChannelTuple that only contains the selected names.
+
+        Args:
+            *names: channel names
+
+        """
+        if len(names) == 0:
+            raise TypeError("one or more names must be given")
+        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,
+        )
+
     def get_channel_by_name(self: Self, *names: str) -> InstrumentModuleType | Self:
         """
         Get a channel by name, or a ChannelTuple if multiple names are given.
@@ -347,9 +368,15 @@ def get_channel_by_name(self: Self, *names: str) -> InstrumentModuleType | Self:
 
         """
         if len(names) == 0:
-            raise Exception("one or more names must be given")
+            raise TypeError("one or more names must be given")
         if len(names) == 1:
             return self._channel_mapping[names[0]]
+
+        warnings.warn(
+            "Supplying more than one name to get_channel_by_name is deprecated, use get_channels_by_name instead",
+            category=QCoDeSDeprecationWarning,
+        )
+
         selected_channels = tuple(self._channel_mapping[name] for name in names)
         return type(self)(
             self._parent,