[core] Add reference to attribute's instance type in descriptions

meshroom/core/attribute.py

@@ -25,17 +25,7 @@ def attributeFactory(description, value, isOutput, node, root=None, parent=None)
         root: (optional) parent Attribute (must be ListAttribute or GroupAttribute)
         parent (BaseObject): (optional) the parent BaseObject if any
     """
-    if isinstance(description, desc.GroupAttribute):
-        cls = GroupAttribute
-    elif isinstance(description, desc.ListAttribute):
-        cls = ListAttribute
-    elif isinstance(description, desc.ChoiceParam):
-        cls = ChoiceParam
-    elif isinstance(description, desc.PushButtonParam):
-        cls = PushButtonParam
-    else:
-        cls = Attribute
-    attr = cls(node, description, isOutput, root, parent)
+    attr = description.instanceType(node, description, isOutput, root, parent)
     if value is not None:
         attr._set_value(value, emitSignals=False)
     else:

meshroom/core/desc.py

@@ -58,6 +58,12 @@ class Attribute(BaseObject):
     visible = Property(bool, lambda self: self._visible, constant=True)
     type = Property(str, lambda self: self.__class__.__name__, constant=True)
 
+    def getInstanceType(self):
+        """ Return the correct Attribute instance corresponding to the description. """
+        # Import within the method to prevent cyclic dependencies
+        from meshroom.core.attribute import Attribute
+        return Attribute
+
     def validateValue(self, value):
         """ Return validated/conformed 'value'. Need to be implemented in derived classes.
 
@@ -88,6 +94,10 @@ class Attribute(BaseObject):
             return False
         return True
 
+    # instanceType
+    #   Attribute instance corresponding to the description
+    instanceType = Property(Variant, lambda self: self.getInstanceType(), constant=True)
+
 
 class ListAttribute(Attribute):
     """ A list of Attributes """
@@ -103,6 +113,11 @@ class ListAttribute(Attribute):
     uid = Property(Variant, lambda self: self.elementDesc.uid, constant=True)
     joinChar = Property(str, lambda self: self._joinChar, constant=True)
 
+    def getInstanceType(self):
+        # Import within the method to prevent cyclic dependencies
+        from meshroom.core.attribute import ListAttribute
+        return ListAttribute
+
     def validateValue(self, value):
         if value is None:
             return value
@@ -144,6 +159,11 @@ class GroupAttribute(Attribute):
 
     groupDesc = Property(Variant, lambda self: self._groupDesc, constant=True)
 
+    def getInstanceType(self):
+        # Import within the method to prevent cyclic dependencies
+        from meshroom.core.attribute import GroupAttribute
+        return GroupAttribute
+
     def validateValue(self, value):
         if value is None:
             return value
@@ -336,11 +356,18 @@ class PushButtonParam(Param):
         super(PushButtonParam, self).__init__(name=name, label=label, description=description, value=None, uid=uid, group=group, advanced=advanced, semantic=semantic, enabled=enabled, visible=visible)
         self._valueType = None
 
+    def getInstanceType(self):
+        # Import within the method to prevent cyclic dependencies
+        from meshroom.core.attribute import PushButtonParam
+        return PushButtonParam
+
     def validateValue(self, value):
         return value
+
     def checkValueTypes(self):
         pass
 
+
 class ChoiceParam(Param):
     """
     """
@@ -362,6 +389,11 @@ class ChoiceParam(Param):
         else:
             self._valueType = type(self._value)
 
+    def getInstanceType(self):
+        # Import within the method to prevent cyclic dependencies
+        from meshroom.core.attribute import ChoiceParam
+        return ChoiceParam
+
     def conformValue(self, value):
         """ Conform 'value' to the correct type and check for its validity """
         # We do not check that the value is in the list of values.