Make sure `Type` subclasses implement the clone method

aesara/graph/type.py

@@ -212,6 +212,10 @@ class Type(MetaObject):
         """
         return self.Constant(type=self, data=value, name=name)
 
+    def clone(self, *args, **kwargs):
+        """Clone a copy of this type with the given arguments/keyword values, if any."""
+        return type(self)(*args, **kwargs)
+
     def __call__(self, name: Optional[Text] = None) -> Variable:
         """Return a new `Variable` instance of Type `self`.
 

aesara/scalar/basic.py

@@ -345,6 +345,11 @@ class Scalar(CType):
         self.dtype = dtype
         self.dtype_specs()  # error checking
 
+    def clone(self, dtype=None, **kwargs):
+        if dtype is None:
+            dtype = self.dtype
+        return type(self)(dtype)
+
     @staticmethod
     def may_share_memory(a, b):
         # This class represent basic c type, represented in python

aesara/sparse/type.py

@@ -89,6 +89,13 @@ class SparseType(Type):
                 list(self.format_cls.keys()),
             )
 
+    def clone(self, format=None, dtype=None, **kwargs):
+        if format is None:
+            format = self.format
+        if dtype is None:
+            dtype = self.dtype
+        return type(self)(format, dtype)
+
     def filter(self, value, strict=False, allow_downcast=None):
         if (
             isinstance(value, self.format_cls[self.format])

aesara/tensor/type_other.py

@@ -52,6 +52,9 @@ make_slice = MakeSlice()
 
 
 class SliceType(Type):
+    def clone(self, **kwargs):
+        return type(self)()
+
     def filter(self, x, strict=False, allow_downcast=None):
         if isinstance(x, slice):
             return x

tests/graph/test_types.py

@@ -67,6 +67,11 @@ def test_convert_variable():
         t1.convert_variable(v3)
 
 
+def test_default_clone():
+    mt = MyType(1)
+    assert isinstance(mt.clone(1), MyType)
+
+
 @pytest.mark.skipif(
     not aesara.config.cxx, reason="G++ not available, so we need to skip this test."
 )

tests/scalar/test_type.py

@@ -60,3 +60,9 @@ def test_filter_float_subclass():
     with config.change_flags(floatX="float64"):
         filtered_nan = test_type.filter(nan)
         assert isinstance(filtered_nan, np.floating)
+
+
+def test_clone():
+    st = Scalar("int64")
+    assert st == st.clone()
+    assert st.clone("float64").dtype == "float64"

tests/sparse/test_type.py

-def test_sparse_type():
-    import aesara.sparse
+from aesara.sparse.type import SparseType
 
-    # They need to be available even if scipy is not available.
-    assert hasattr(aesara.sparse, "SparseType")
+
+def test_clone():
+    st = SparseType("csr", "float64")
+    assert st == st.clone()