fix(python): Don't consume c_stream as iterable

py-polars/polars/dataframe/frame.py

@@ -408,7 +408,11 @@ def __init__(
                 data, schema=schema, schema_overrides=schema_overrides, strict=strict
             )
 
-        elif not isinstance(data, Sized) and isinstance(data, (Generator, Iterable)):
+        elif (
+            not hasattr(data, "__arrow_c_stream__")
+            and not isinstance(data, Sized)
+            and isinstance(data, (Generator, Iterable))
+        ):
             self._df = iterable_to_pydf(
                 data,
                 schema=schema,

py-polars/polars/series/series.py

@@ -329,7 +329,7 @@ def __init__(
         ):
             self._s = pandas_to_pyseries(name, values, dtype=dtype, strict=strict)
 
-        elif _is_generator(values):
+        elif not hasattr(values, "__arrow_c_stream__") and _is_generator(values):
             self._s = iterable_to_pyseries(name, values, dtype=dtype, strict=strict)
 
         elif isinstance(values, Series):

py-polars/tests/unit/constructors/test_constructors.py

@@ -1703,7 +1703,7 @@ class PyCapsuleStreamHolder:
     """
     Hold the Arrow C Stream pycapsule.
 
-    A class that exposes _only_ the Arrow C Stream interface via Arrow PyCapsules. This
+    A class that exposes the Arrow C Stream interface via Arrow PyCapsules. This
     ensures that the consumer is seeing _only_ the `__arrow_c_stream__` dunder, and that
     nothing else (e.g. the dataframe or array interface) is actually being used.
     """
@@ -1716,6 +1716,12 @@ def __init__(self, arrow_obj: object) -> None:
     def __arrow_c_stream__(self, requested_schema: object = None) -> object:
         return self.arrow_obj.__arrow_c_stream__(requested_schema)
 
+    def __iter__(self) -> None:
+        return
+
+    def __next__(self) -> None:
+        return
+
 
 class PyCapsuleArrayHolder:
     """