Add meaningful "representation" formatter to object classes (#432)

Add __repr__() method for the object classes *Variable(), *Array() and *Record().  Extend ODVariable with a ".qualname" attribute which prepends the parent's name with a dot.

canopen/objectdictionary/__init__.py

@@ -176,6 +176,9 @@ def __init__(self, name: str, index: int):
         self.subindices = {}
         self.names = {}
 
+    def __repr__(self) -> str:
+        return f"<{type(self).__qualname__} {self.name!r} at 0x{self.index:04X}>"
+
     def __getitem__(self, subindex: Union[int, str]) -> "ODVariable":
         item = self.names.get(subindex) or self.subindices.get(subindex)
         if item is None:
@@ -232,6 +235,9 @@ def __init__(self, name: str, index: int):
         self.subindices = {}
         self.names = {}
 
+    def __repr__(self) -> str:
+        return f"<{type(self).__qualname__} {self.name!r} at 0x{self.index:04X}>"
+
     def __getitem__(self, subindex: Union[int, str]) -> "ODVariable":
         var = self.names.get(subindex) or self.subindices.get(subindex)
         if var is not None:
@@ -327,6 +333,17 @@ def __init__(self, name: str, index: int, subindex: int = 0):
         #: Can this variable be mapped to a PDO
         self.pdo_mappable = False
 
+    def __repr__(self) -> str:
+        suffix = f":{self.subindex:02X}" if isinstance(self.parent, (ODRecord, ODArray)) else ""
+        return f"<{type(self).__qualname__} {self.qualname!r} at 0x{self.index:04X}{suffix}>"
+
+    @property
+    def qualname(self) -> str:
+        """Fully qualified name of the variable. If the variable is a subindex
+        of a record or array, the name will be prefixed with the parent's name."""
+        if isinstance(self.parent, (ODRecord, ODArray)):
+            return f"{self.parent.name}.{self.name}"
+        return self.name
 
     def __eq__(self, other: "ODVariable") -> bool:
         return (self.index == other.index and

canopen/pdo/base.py

@@ -191,6 +191,9 @@ def __init__(self, pdo_node, com_record, map_array):
         self.is_received: bool = False
         self._task = None
 
+    def __repr__(self) -> str:
+        return f"<{type(self).__qualname__} {self.name!r} at COB-ID 0x{self.cob_id:X}>"
+
     def __getitem_by_index(self, value):
         valid_values = []
         for var in self.map:

canopen/sdo/base.py

@@ -96,6 +96,9 @@ def __init__(self, sdo_node: SdoBase, od: ObjectDictionary):
         self.sdo_node = sdo_node
         self.od = od
 
+    def __repr__(self) -> str:
+        return f"<{type(self).__qualname__} {self.od.name!r} at 0x{self.od.index:04X}>"
+
     def __getitem__(self, subindex: Union[int, str]) -> "SdoVariable":
         return SdoVariable(self.sdo_node, self.od[subindex])
 
@@ -115,6 +118,9 @@ def __init__(self, sdo_node: SdoBase, od: ObjectDictionary):
         self.sdo_node = sdo_node
         self.od = od
 
+    def __repr__(self) -> str:
+        return f"<{type(self).__qualname__} {self.od.name!r} at 0x{self.od.index:04X}>"
+
     def __getitem__(self, subindex: Union[int, str]) -> "SdoVariable":
         return SdoVariable(self.sdo_node, self.od[subindex])
 

canopen/variable.py

@@ -22,6 +22,12 @@ def __init__(self, od: objectdictionary.ODVariable):
         #: Holds a local, overridable copy of the Object Subindex
         self.subindex = od.subindex
 
+    def __repr__(self) -> str:
+        suffix = f":{self.subindex:02X}" if isinstance(self.od.parent,
+            (objectdictionary.ODRecord, objectdictionary.ODArray)
+        ) else ""
+        return f"<{type(self).__qualname__} {self.name!r} at 0x{self.index:04X}{suffix}>"
+
     def get_data(self) -> bytes:
         raise NotImplementedError("Variable is not readable")