fix: Simplify missing gates handling

src/qibolab/compilers/default.py

@@ -30,17 +30,16 @@ def identity_rule(gate: Gate, natives: SingleQubitNatives) -> PulseSequence:
 
 def gpi2_rule(gate: Gate, natives: SingleQubitNatives) -> PulseSequence:
     """Rule for GPI2."""
-    assert natives.RX is not None
-    return natives.RX.create_sequence(theta=np.pi / 2, phi=gate.parameters[0])
+    return natives.ensure("RX").create_sequence(theta=np.pi / 2, phi=gate.parameters[0])
 
 
-def gpi_rule(gate: Gate, qubit: Qubit) -> PulseSequence:
+def gpi_rule(gate: Gate, natives: SingleQubitNatives) -> PulseSequence:
     """Rule for GPI."""
     # the following definition has a global phase difference compare to
     # to the matrix representation. See
     # https://github.com/qiboteam/qibolab/pull/804#pullrequestreview-1890205509
     # for more detail.
-    return qubit.RX.create_sequence(theta=np.pi, phi=gate.parameters[0])
+    return natives.ensure("RX").create_sequence(theta=np.pi, phi=gate.parameters[0])
 
 
 def cz_rule(gate: Gate, natives: TwoQubitNatives) -> PulseSequence:
@@ -49,22 +48,19 @@ def cz_rule(gate: Gate, natives: TwoQubitNatives) -> PulseSequence:
     Applying the CZ gate may involve sending pulses on qubits that the
     gate is not directly acting on.
     """
-    assert natives.CZ is not None
-    return natives.CZ.create_sequence()
+    return natives.ensure("CZ").create_sequence()
 
 
 def cnot_rule(gate: Gate, natives: TwoQubitNatives) -> PulseSequence:
     """CNOT applied as defined in the platform runcard."""
-    assert natives.CNOT is not None
-    return natives.CNOT.create_sequence()
+    return natives.ensure("CNOT").create_sequence()
 
 
 def measurement_rule(gate: Gate, natives: list[SingleQubitNatives]) -> PulseSequence:
     """Measurement gate applied using the platform readout pulse."""
     seq = PulseSequence()
     for qubit in natives:
-        assert qubit.MZ is not None
-        seq.concatenate(qubit.MZ.create_sequence())
+        seq.concatenate(qubit.ensure("MZ").create_sequence())
     return seq
 
 

src/qibolab/native.py

@@ -1,3 +1,4 @@
+from abc import ABC, abstractmethod
 from typing import Annotated, Optional
 
 import numpy as np
@@ -14,7 +15,13 @@ def _normalize_angles(theta, phi):
     return theta, phi
 
 
-class RxyFactory(PulseSequence):
+class Native(ABC, PulseSequence):
+    @abstractmethod
+    def create_sequence(self, *args, **kwargs) -> PulseSequence:
+        """Create a sequence for single-qubit rotation."""
+
+
+class RxyFactory(Native):
     """Factory for pulse sequences that generate single-qubit rotations around
     an axis in xy plane.
 
@@ -66,14 +73,29 @@ def create_sequence(self, theta: float = np.pi, phi: float = 0.0) -> PulseSequen
         )
 
 
-class FixedSequenceFactory(PulseSequence):
+class FixedSequenceFactory(Native):
     """Simple factory for a fixed arbitrary sequence."""
 
     def create_sequence(self) -> PulseSequence:
         return self.copy()
 
 
-class SingleQubitNatives(Model):
+class MissingNative(RuntimeError):
+    """Missing native gate."""
+
+    def __init__(self, gate: str):
+        super().__init__(f"Native gate definition not found, for gate {gate}")
+
+
+class NativeContainer(Model):
+    def ensure(self, name: str) -> Native:
+        value = getattr(self, name)
+        if value is None:
+            raise MissingNative(value)
+        return value
+
+
+class SingleQubitNatives(NativeContainer):
     """Container with the native single-qubit gates acting on a specific
     qubit."""
 
@@ -87,7 +109,7 @@ class SingleQubitNatives(Model):
     """Pulse to activate coupler."""
 
 
-class TwoQubitNatives(Model):
+class TwoQubitNatives(NativeContainer):
     """Container with the native two-qubit gates acting on a specific pair of
     qubits."""