handling of errors

Author: lfarv

pyat/at/latticetools/observablelist.py

@@ -49,21 +49,15 @@ def __init__(self, obsiter):
         self.base = obsiter
 
     def __next__(self):
-        val = next(self.base)
-        if isinstance(val, Exception):
-            raise val
-        return val
+        return Observable.check_value(next(self.base))
 
 
 class _ObsResults(tuple):
     def __getitem__(self, item):
         if isinstance(item, slice):
             return _ObsResults(super().__getitem__(item))
         else:
-            val = super().__getitem__(item)
-            if isinstance(val, Exception):
-                raise type(val)(val.args[0]) from val
-            return val
+            return Observable.check_value(super().__getitem__(item))
 
     def __iter__(self):
         return _ObsResIter(super().__iter__())

pyat/at/latticetools/observables.py

@@ -353,13 +353,16 @@ def check(self) -> bool:
         """
         return self.value is not None
 
+    @staticmethod
+    def check_value(value):
+        if isinstance(value, Exception):
+            raise type(value)(value.args[0]) from value
+        return value
+
     @property
     def value(self):
         """Value of the observable."""
-        val = self._value
-        if isinstance(val, Exception):
-            raise type(val)(val.args[0]) from val
-        return val
+        return self.check_value(self._value)
 
     @property
     def weight(self):
@@ -528,7 +531,9 @@ def check(self):
         ok = super().check()
         shp = self._shape
         if ok and shp and shp[0] <= 0:
-            raise AtError(f"Observable {self.name!r}: No location selected in the lattice.")
+            raise AtError(
+                f"Observable {self.name!r}: No location selected in the lattice."
+            )
         return ok
 
     def _all_lines(self):