Remove public fields for measurement and controlled ops (quantumlib#5061

)

Change public fields to private, and encapsulate with getters and deprecated setters.

xref quantumlib#4851

cirq/ops/controlled_gate.py

@@ -18,6 +18,7 @@
 
 import cirq
 from cirq import protocols, value
+from cirq._compat import deprecated
 from cirq.ops import raw_types, controlled_operation as cop
 from cirq.type_workarounds import NotImplementedType
 
@@ -73,10 +74,10 @@ def __init__(
             control_qid_shape = (2,) * num_controls
         if num_controls != len(control_qid_shape):
             raise ValueError('len(control_qid_shape) != num_controls')
-        self.control_qid_shape = tuple(control_qid_shape)
+        self._control_qid_shape = tuple(control_qid_shape)
 
         # Convert to sorted tuples
-        self.control_values = cast(
+        self._control_values = cast(
             Tuple[Tuple[int, ...], ...],
             tuple((val,) if isinstance(val, int) else tuple(sorted(val)) for val in control_values),
         )
@@ -90,11 +91,47 @@ def __init__(
 
         # Flatten nested ControlledGates.
         if isinstance(sub_gate, ControlledGate):
-            self.sub_gate = sub_gate.sub_gate  # type: ignore
-            self.control_values += sub_gate.control_values
-            self.control_qid_shape += sub_gate.control_qid_shape
+            self._sub_gate = sub_gate.sub_gate  # type: ignore
+            self._control_values += sub_gate.control_values
+            self._control_qid_shape += sub_gate.control_qid_shape
         else:
-            self.sub_gate = sub_gate
+            self._sub_gate = sub_gate
+
+    @property
+    def control_qid_shape(self) -> Tuple[int, ...]:
+        return self._control_qid_shape
+
+    @control_qid_shape.setter  # type: ignore
+    @deprecated(
+        deadline="v0.15",
+        fix="The mutators of this class are deprecated, instantiate a new object instead.",
+    )
+    def control_qid_shape(self, control_qid_shape: Tuple[int, ...]):
+        self._control_qid_shape = control_qid_shape
+
+    @property
+    def control_values(self) -> Tuple[Tuple[int, ...], ...]:
+        return self._control_values
+
+    @control_values.setter  # type: ignore
+    @deprecated(
+        deadline="v0.15",
+        fix="The mutators of this class are deprecated, instantiate a new object instead.",
+    )
+    def control_values(self, control_values: Tuple[Tuple[int, ...], ...]):
+        self._control_values = control_values
+
+    @property
+    def sub_gate(self) -> 'cirq.Gate':
+        return self._sub_gate
+
+    @sub_gate.setter  # type: ignore
+    @deprecated(
+        deadline="v0.15",
+        fix="The mutators of this class are deprecated, instantiate a new object instead.",
+    )
+    def sub_gate(self, sub_gate: 'cirq.Gate'):
+        self._sub_gate = sub_gate
 
     def num_controls(self) -> int:
         return len(self.control_qid_shape)

cirq/ops/controlled_gate_test.py

@@ -555,3 +555,16 @@ def num_qubits(self) -> int:
             (0.25, cirq.unitary(cirq.CZ)),
         ],
     )
+
+
+def test_setters_deprecated():
+    gate = cirq.ControlledGate(cirq.Z)
+    with cirq.testing.assert_deprecated('mutators', deadline='v0.15'):
+        gate.sub_gate = cirq.X
+    assert gate.sub_gate == cirq.X
+    with cirq.testing.assert_deprecated('mutators', deadline='v0.15'):
+        gate.control_qid_shape = (3, 3)
+    assert gate.control_qid_shape == (3, 3)
+    with cirq.testing.assert_deprecated('mutators', deadline='v0.15'):
+        gate.control_values = ((3,), (3,))
+    assert gate.control_values == ((3,), (3,))

cirq/ops/controlled_operation.py

@@ -29,6 +29,7 @@
 import numpy as np
 
 from cirq import protocols, qis, value
+from cirq._compat import deprecated
 from cirq.ops import raw_types, gate_operation, controlled_gate
 from cirq.type_workarounds import NotImplementedType
 
@@ -54,7 +55,7 @@ def __init__(
         if len(control_values) != len(controls):
             raise ValueError('len(control_values) != len(controls)')
         # Convert to sorted tuples
-        self.control_values = cast(
+        self._control_values = cast(
             Tuple[Tuple[int, ...], ...],
             tuple((val,) if isinstance(val, int) else tuple(sorted(val)) for val in control_values),
         )
@@ -64,13 +65,49 @@ def __init__(
                 raise ValueError(f'Control values <{val!r}> outside of range for qubit <{q!r}>.')
 
         if not isinstance(sub_operation, ControlledOperation):
-            self.controls = tuple(controls)
-            self.sub_operation = sub_operation
+            self._controls = tuple(controls)
+            self._sub_operation = sub_operation
         else:
             # Auto-flatten nested controlled operations.
-            self.controls = tuple(controls) + sub_operation.controls
-            self.sub_operation = sub_operation.sub_operation
-            self.control_values += sub_operation.control_values
+            self._controls = tuple(controls) + sub_operation.controls
+            self._sub_operation = sub_operation.sub_operation
+            self._control_values += sub_operation.control_values
+
+    @property
+    def controls(self) -> Tuple['cirq.Qid', ...]:
+        return self._controls
+
+    @controls.setter  # type: ignore
+    @deprecated(
+        deadline="v0.15",
+        fix="The mutators of this class are deprecated, instantiate a new object instead.",
+    )
+    def controls(self, controls: Tuple['cirq.Qid', ...]):
+        self._controls = controls
+
+    @property
+    def control_values(self) -> Tuple[Tuple[int, ...], ...]:
+        return self._control_values
+
+    @control_values.setter  # type: ignore
+    @deprecated(
+        deadline="v0.15",
+        fix="The mutators of this class are deprecated, instantiate a new object instead.",
+    )
+    def control_values(self, control_values: Tuple[Tuple[int, ...], ...]):
+        self._control_values = control_values
+
+    @property
+    def sub_operation(self) -> 'cirq.Operation':
+        return self._sub_operation
+
+    @sub_operation.setter  # type: ignore
+    @deprecated(
+        deadline="v0.15",
+        fix="The mutators of this class are deprecated, instantiate a new object instead.",
+    )
+    def sub_operation(self, sub_operation: 'cirq.Operation'):
+        self._sub_operation = sub_operation
 
     @property
     def gate(self) -> Optional['cirq.ControlledGate']:

cirq/ops/controlled_operation_test.py

@@ -397,3 +397,17 @@ def with_qubits(self, *new_qubits):
             (0.25, cirq.unitary(cirq.CZ)),
         ],
     )
+
+
+def test_setters_deprecated():
+    q0, q1, q2 = cirq.LineQubit.range(3)
+    op = cirq.ControlledOperation([q1], cirq.Z(q0))
+    with cirq.testing.assert_deprecated('mutators', deadline='v0.15'):
+        op.sub_operation = cirq.X(q0)
+    assert op.sub_operation == cirq.X(q0)
+    with cirq.testing.assert_deprecated('mutators', deadline='v0.15'):
+        op.controls = (q2,)
+    assert op.controls == (q2,)
+    with cirq.testing.assert_deprecated('mutators', deadline='v0.15'):
+        op.control_values = ((3,), (3,))
+    assert op.control_values == ((3,), (3,))

cirq/ops/measurement_gate.py

@@ -17,6 +17,7 @@
 import numpy as np
 
 from cirq import protocols, value
+from cirq._compat import deprecated
 from cirq.ops import raw_types
 
 if TYPE_CHECKING:
@@ -65,21 +66,51 @@ def __init__(
         self._qid_shape = qid_shape
         if len(self._qid_shape) != num_qubits:
             raise ValueError('len(qid_shape) != num_qubits')
-        self.key = key  # type: ignore
-        self.invert_mask = invert_mask or ()
+        self._mkey = (
+            key if isinstance(key, value.MeasurementKey) else value.MeasurementKey(name=key)
+        )
+        self._invert_mask = invert_mask or ()
         if self.invert_mask is not None and len(self.invert_mask) > self.num_qubits():
             raise ValueError('len(invert_mask) > num_qubits')
 
     @property
     def key(self) -> str:
         return str(self.mkey)
 
-    @key.setter
+    @key.setter  # type: ignore
+    @deprecated(
+        deadline="v0.15",
+        fix="The mutators of this class are deprecated, instantiate a new object instead.",
+    )
     def key(self, key: Union[str, 'cirq.MeasurementKey']):
         if isinstance(key, value.MeasurementKey):
-            self.mkey = key
+            self._mkey = key
         else:
-            self.mkey = value.MeasurementKey(name=key)
+            self._mkey = value.MeasurementKey(name=key)
+
+    @property
+    def mkey(self) -> 'cirq.MeasurementKey':
+        return self._mkey
+
+    @mkey.setter  # type: ignore
+    @deprecated(
+        deadline="v0.15",
+        fix="The mutators of this class are deprecated, instantiate a new object instead.",
+    )
+    def mkey(self, mkey: 'cirq.MeasurementKey'):
+        self._mkey = mkey
+
+    @property
+    def invert_mask(self) -> Tuple[bool, ...]:
+        return self._invert_mask
+
+    @invert_mask.setter  # type: ignore
+    @deprecated(
+        deadline="v0.15",
+        fix="The mutators of this class are deprecated, instantiate a new object instead.",
+    )
+    def invert_mask(self, invert_mask: Tuple[bool, ...]):
+        self._invert_mask = invert_mask
 
     def _qid_shape_(self) -> Tuple[int, ...]:
         return self._qid_shape

cirq/ops/measurement_gate_test.py

@@ -462,3 +462,22 @@ def test_act_on_qutrit():
     )
     cirq.act_on(m, args)
     assert args.log_of_measurement_results == {'out': [0, 2]}
+
+
+def test_setters_deprecated():
+    gate = cirq.MeasurementGate(1, key='m', invert_mask=(False,))
+    with cirq.testing.assert_deprecated('mutators', deadline='v0.15'):
+        gate.key = 'n'
+    assert gate.key == 'n'
+    assert gate.mkey == cirq.MeasurementKey('n')
+    with cirq.testing.assert_deprecated('mutators', deadline='v0.15'):
+        gate.key = cirq.MeasurementKey('o')
+    assert gate.key == 'o'
+    assert gate.mkey == cirq.MeasurementKey('o')
+    with cirq.testing.assert_deprecated('mutators', deadline='v0.15'):
+        gate.mkey = cirq.MeasurementKey('p')
+    assert gate.key == 'p'
+    assert gate.mkey == cirq.MeasurementKey('p')
+    with cirq.testing.assert_deprecated('mutators', deadline='v0.15'):
+        gate.invert_mask = (True,)
+    assert gate.invert_mask == (True,)