Preserve declared base class order for DataItem collection in multiple inheritance

collect_items_in_bases_order now ensures DataItems are collected according to
the order bases are listed in class declarations, matching developer expectations
in multiple inheritance scenarios.

Fix #92

Author: PierreRaybaut

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Changelog #
 
+## Version 3.12.1 ##
+
+🛠️ Bug fixes:
+
+* [Issue #92](https://github.com/PlotPyStack/guidata/issues/92) - Changing base class order in DataSet inheritance does not affect item order as expected
+  * When using multiple inheritance with DataSet classes, changing the order of the base classes in the child class definition did not affect the order of the items in the resulting dataset.
+  * One would expect the items to appear in the order in which the base classes are listed, and thanks to this fix, this is now the case.
+
 ## Version 3.12.0 ##
 
 💥 New features:

guidata/dataset/datatypes.py

@@ -1018,6 +1018,31 @@ def label(self) -> str:
         return self.item.get_prop("display", "label")
 
 
+def collect_items_in_bases_order(
+    bases: tuple[type], seen: set | None = None
+) -> list[DataItem]:
+    """Collect items in bases order
+
+    Args:
+        bases: tuple of base classes
+        seen: set of already seen items to avoid duplicates
+
+    Returns:
+        List of data items
+    """
+    if seen is None:
+        seen = set()
+    items = []
+    for base in bases:
+        items.extend(collect_items_in_bases_order(base.__bases__, seen))
+        base_dict = getattr(base, "__dict__", {})
+        for name, obj in base_dict.items():
+            if isinstance(obj, DataItem) and name not in seen:
+                items.append(obj)
+                seen.add(name)
+    return items
+
+
 class DataSetMeta(type):
     """
     DataSet metaclass
@@ -1027,12 +1052,7 @@ class DataSetMeta(type):
     """
 
     def __new__(cls: type, name: str, bases: Any, dct: dict[str, Any]) -> type:
-        items = {}
-        for base in bases:
-            if getattr(base, "__metaclass__", None) is DataSetMeta:
-                for item in base._items:
-                    items[item._name] = item
-
+        items = {item._name: item for item in collect_items_in_bases_order(bases)}
         for attrname, value in list(dct.items()):
             if isinstance(value, DataItem):
                 value.set_name(attrname)

guidata/tests/dataset/test_inheritance.py

@@ -17,17 +17,15 @@
 from guidata.qthelpers import qt_app_context
 
 
-class OriginalDataset(gds.DataSet):
+class OriginalDataset1(gds.DataSet):
     """Original dataset
     This is the original dataset"""
 
-    bool = gds.BoolItem("Boolean")
-    string = gds.StringItem("String")
-    text = gds.TextItem("Text")
-    float = gds.FloatItem("Float", default=0.5, min=0, max=1, step=0.01, slider=True)
+    text1 = gds.TextItem("Text 1")
+    int1 = gds.IntItem("Integer 1", default=111)
 
 
-class DerivedDataset(OriginalDataset):
+class DerivedDataset(OriginalDataset1):
     """Derived dataset
     This is the derived dataset"""
 
@@ -40,7 +38,7 @@ class DerivedDataset(OriginalDataset):
 def test_inheritance():
     """Test DataSet inheritance"""
     with qt_app_context():
-        e = OriginalDataset()
+        e = OriginalDataset1()
         e.edit()
         execenv.print(e)
 
@@ -50,5 +48,43 @@ def test_inheritance():
         execenv.print("OK")
 
 
+class OriginalDataset2(gds.DataSet):
+    """Original dataset 2
+    This is another original dataset"""
+
+    text2 = gds.TextItem("Text 2")
+    int2 = gds.IntItem("Integer 2", default=222)
+
+
+class DoubleInheritedDataset1(OriginalDataset1, OriginalDataset2):
+    """Double inherited dataset
+    This is a dataset that inherits from two original datasets"""
+
+    text3 = gds.TextItem("Text 3")
+    int3 = gds.IntItem("Integer 3", default=333)
+
+
+class DoubleInheritedDataset2(OriginalDataset2, OriginalDataset1):
+    """Double inherited dataset 2
+    This is a dataset that inherits from two original datasets in reverse order"""
+
+    text4 = gds.TextItem("Text 4")
+    int4 = gds.IntItem("Integer 4", default=444)
+
+
+def test_double_inheritance():
+    """Test DataSet double inheritance"""
+    with qt_app_context():
+        e = DoubleInheritedDataset1()
+        e.edit()
+        execenv.print(e)
+
+        e = DoubleInheritedDataset2()
+        e.edit()
+        execenv.print(e)
+        execenv.print("OK")
+
+
 if __name__ == "__main__":
+    test_double_inheritance()
     test_inheritance()