Fix #3261

hyperspy/component.py

@@ -721,11 +721,12 @@ def default_traits_view(self):
 @add_gui_method(toolkey="hyperspy.Component")
 class Component(t.HasTraits):
     __axes_manager = None
+    # setting dtype for t.Property(t.Bool) causes serialization error with cloudpickle
+    active = t.Property()
+    name = t.Property()
 
-    active = t.Property(t.CBool(True))
-    name = t.Property(t.Str(''))
-
-    def __init__(self, parameter_name_list, linear_parameter_list=None):
+    def __init__(self, parameter_name_list, linear_parameter_list=None, *args, **kwargs):
+        super().__init__(*args, **kwargs)
         self.events = Events()
         self.events.active_changed = Event("""
             Event that triggers when the `Component.active` changes.
@@ -806,6 +807,8 @@ def _get_name(self):
         return self._name
 
     def _set_name(self, value):
+        if not isinstance(value, str):
+            raise ValueError('Only string values are permitted')
         old_value = self._name
         if old_value == value:
             return

hyperspy/model.py

@@ -125,7 +125,14 @@ def reconstruct_component(comp_dictionary, **init_args):
     elif "_class_dump" in comp_dictionary:
         # When a component is not registered using the extension mechanism,
         # it is serialized using cloudpickle.
-        _class = cloudpickle.loads(comp_dictionary['_class_dump'])
+        try:
+            _class = cloudpickle.loads(comp_dictionary['_class_dump'])
+        except TypeError:  # pragma: no cover
+            # https://github.com/cloudpipe/cloudpickle/blob/master/README.md
+            raise TypeError("Pickling is not (always) supported between python "
+                            "versions. As a result the custom class cannot be "
+                            "loaded. Consider adding a custom Component using the "
+                            "extension mechanism.")
     else:
         # For component saved with hyperspy <2.0 and moved to exspy
         if comp_dictionary["_id_name"] in EXSPY_HSPY_COMPONENTS:

hyperspy/tests/component/test_component.py

@@ -18,14 +18,18 @@
 
 import pytest
 from unittest import mock
+import pathlib
 
 import numpy as np
 
+import hyperspy.api as hs
 from hyperspy.axes import AxesManager
 from hyperspy.component import Component, Parameter, _get_scaling_factor
 from hyperspy._signals.signal1d import Signal1D
 
 
+DIRPATH = pathlib.Path(__file__).parent / "data"
+
 class TestMultidimensionalActive:
 
     def setup_method(self, method):
@@ -298,3 +302,66 @@ def test_linear_parameter_initialisation():
     assert C.one._linear
     assert not C.two._linear
     assert not P._linear
+
+
+def test_set_name():
+    c = Component(['one', 'two'], ['one'])
+    c.name = 'test'
+    assert c.name == 'test'
+    assert c._name == 'test'
+
+
+def test_set_name_error():
+    c = Component(['one', 'two'], ['one'])
+    with pytest.raises(ValueError):
+        c.name = 1
+
+
+def test_loading_non_expression_custom_component(tmp_path):
+    # non-expression based custom component uses serialisation
+    # to save the components.
+
+    import hyperspy.api as hs
+    from hyperspy.component import Component
+
+    class CustomComponent(Component):
+
+        def __init__(self, p1=1, p2=2):
+            Component.__init__(self, ('p1', 'p2'))
+
+            self.p1.value = p1
+            self.p2.value = p2
+
+            self.p1.grad = self.grad_p1
+            self.p2.grad = self.grad_p2
+
+        def function(self, x):
+            p1 = self.p1.value
+            p2 = self.p2.value
+            return p1 + x * p2
+
+        def grad_p1(self, x):
+            return 0
+
+        def grad_p2(self, x):
+            return x
+
+    s = hs.signals.Signal1D(range(10))
+    m = s.create_model()
+
+    c = CustomComponent()
+    m.append(c)
+    m.store('a')
+
+    s.save(tmp_path / "hs2.0_custom_component.hspy")
+
+    s = hs.load(tmp_path / "hs2.0_custom_component.hspy")
+    _ = s.models.restore('a')
+
+
+def test_load_component_previous_python():
+    s = hs.load(DIRPATH / "hs2.0_custom_component.hspy")
+    import sys
+    if sys.version_info[0] == 3.11:
+        with pytest.raises(TypeError):
+            _ = s.models.restore('a')

upcoming_changes/3262.bugfix.rst

@@ -0,0 +1,2 @@
+Fix serialization error due to :py:class:`traits.api.Property` not being serializable if a dtype is specified.
+See #3261 for more details.