Deprecate ordering

py-polars/polars/datatypes/classes.py

@@ -523,8 +523,11 @@ class Array(NestedType):
     inner: PolarsDataType | None = None
     width: int
 
-    def __init__(
-        self, width: int, inner: PolarsDataType | PythonDataType | None = None
+    def __init__(  # noqa: D417
+        self,
+        *args: Any,
+        width: int | None = None,
+        inner: PolarsDataType | PythonDataType | None = None,
     ):
         """
         Fixed length list type.
@@ -550,9 +553,22 @@ def __init__(
         ]
 
         """
-        if inner is None:
-            from polars.utils.deprecation import issue_deprecation_warning
+        from polars.utils.deprecation import issue_deprecation_warning
 
+        if args:
+            issue_deprecation_warning(
+                "Parameters `inner` and `width` will change positions in the next breaking release."
+                " Use keyword arguments to keep current behavior and silence this warning.",
+                version="0.19.11",
+            )
+            if len(args) == 1:
+                width = args[0]
+            else:
+                width, inner = args[:2]
+        elif width is None:
+            raise TypeError("`width` must be specified when initializing an `Array`")
+
+        if inner is None:
             issue_deprecation_warning(
                 "The default value for the `inner` parameter of `Array` will be removed in the next breaking release."
                 " Pass `inner=pl.Null`to keep current behavior and silence this warning.",

py-polars/tests/unit/datatypes/test_array.py

@@ -104,3 +104,14 @@ def test_array_concat() -> None:
     assert pl.concat([a_df, b_df]).to_dict(False) == {
         "a": [[0, 1], [1, 0], [1, 1], [0, 0]]
     }
+
+
+def test_array_init_deprecation() -> None:
+    with pytest.deprecated_call():
+        pl.Array(2)
+    with pytest.deprecated_call():
+        pl.Array(2, pl.Utf8)
+    with pytest.deprecated_call():
+        pl.Array(2, inner=pl.Utf8)
+    with pytest.deprecated_call():
+        pl.Array(width=2)