Fix for empty array

Author: JeanLucPons

pyaml/arrays/bpm_array.py

@@ -77,7 +77,7 @@ def __init__(self, arrayName: str, bpms: list[BPM], use_aggregator=True):
         self.__hpos = RWBPMSinglePosition(arrayName, bpms, 0)
         self.__vpos = RWBPMSinglePosition(arrayName, bpms, 1)
 
-        if use_aggregator:
+        if use_aggregator and len(bpms) > 0:
             aggs = self.get_peer().create_bpm_aggregators(bpms)
             self.__hvpos.set_aggregator(aggs[0])
             self.__hpos.set_aggregator(aggs[1])

pyaml/arrays/element_array.py

@@ -30,14 +30,15 @@ def __init__(self, arrayName: str, elements: list[Element], use_aggregator=True)
         """
         super().__init__(i for i in elements)
         self.__name = arrayName
-        self.__peer = self[0]._peer if len(self) > 0 else None
-        self.__use_aggretator = use_aggregator
-        if self.__peer is None or any([m._peer != self.__peer for m in self]):
-            raise PyAMLException(
-                f"{self.__class__.__name__} {self.get_name()}: "
-                "All elements must be attached to the same instance "
-                "of either a Simulator or a ControlSystem"
-            )
+        if len(elements) > 0:
+            self.__peer = self[0]._peer if len(self) > 0 else None
+            self.__use_aggretator = use_aggregator
+            if self.__peer is None or any([m._peer != self.__peer for m in self]):
+                raise PyAMLException(
+                    f"{self.__class__.__name__} {self.get_name()}: "
+                    "All elements must be attached to the same instance "
+                    "of either a Simulator or a ControlSystem"
+                )
 
     def get_peer(self):
         """

pyaml/arrays/magnet_array.py

@@ -103,7 +103,7 @@ def __init__(self, arrayName: str, magnets: list[Magnet], use_aggregator=True):
         self.__rwstrengths = RWMagnetStrength(arrayName, magnets)
         self.__rwhardwares = RWMagnetHardware(arrayName, magnets)
 
-        if use_aggregator:
+        if use_aggregator and len(magnets) > 0:
             aggs = self.get_peer().create_magnet_strength_aggregator(magnets)
             aggh = self.get_peer().create_magnet_harddware_aggregator(magnets)
             self.__rwstrengths.set_aggregator(aggs)