style: eliminate all type casts

pytket/phir/sharding/sharder.py

@@ -7,7 +7,6 @@
 ##############################################################################
 
 import logging
-from typing import cast
 
 from pytket.circuit import Circuit, Command, Conditional, Op, OpType
 from pytket.unit_id import Bit, Qubit, UnitID
@@ -273,11 +272,8 @@ def should_op_create_shard(op: Op) -> bool:
             `True` if the operation is one that should result in shard creation
         """
         return (
-            op.type in (SHARD_TRIGGER_OP_TYPES)
-            or (
-                op.type == OpType.Conditional
-                and cast(Conditional, op).op.type in (SHARD_TRIGGER_OP_TYPES)
-            )
+            op.type in SHARD_TRIGGER_OP_TYPES
+            or (isinstance(op, Conditional) and op.op.type in SHARD_TRIGGER_OP_TYPES)
             or (op.is_gate() and op.n_qubits > 1)
         )
 
@@ -289,6 +285,5 @@ def _is_command_global_phase(command: Command) -> bool:
             command: Command to evaluate
         """
         return command.op.type == OpType.Phase or (
-            command.op.type == OpType.Conditional
-            and cast(Conditional, command.op).op.type == OpType.Phase
+            isinstance(command.op, Conditional) and command.op.op.type == OpType.Phase
         )

tests/test_sharder.py

@@ -6,8 +6,6 @@
 #
 ##############################################################################
 
-from typing import cast
-
 from pytket.circuit import Conditional, Op, OpType
 from pytket.phir.sharding.sharder import Sharder
 
@@ -126,8 +124,8 @@ def test_simple_conditional(self) -> None:
         assert not shards[1].bits_read
 
         # shard 2: if (c==1) z=1;
-        assert shards[2].primary_command.op.type == OpType.Conditional
-        assert cast(Conditional, shards[2].primary_command.op).op.type == OpType.SetBits
+        assert isinstance(shards[2].primary_command.op, Conditional)
+        assert shards[2].primary_command.op.op.type == OpType.SetBits
         assert not shards[2].sub_commands
         assert not shards[2].qubits_used
         assert shards[2].bits_written == {circuit.bits[1]}
@@ -143,8 +141,8 @@ def test_simple_conditional(self) -> None:
         assert len(shards[3].sub_commands.items()) == 1
         s2_qubit, s2_sub_cmds = next(iter(shards[3].sub_commands.items()))
         assert s2_qubit == circuit.qubits[0]
-        assert s2_sub_cmds[0].op.type == OpType.Conditional
-        assert cast(Conditional, s2_sub_cmds[0].op).op.type == OpType.H
+        assert isinstance(s2_sub_cmds[0].op, Conditional)
+        assert s2_sub_cmds[0].op.op.type == OpType.H
         assert s2_sub_cmds[0].qubits == [circuit.qubits[0]]
 
     def test_complex_barriers(self) -> None:  # noqa: PLR0915