add pycapsulre_failure.py

Author: kosiew

examples/pycapsule_failure.py

@@ -0,0 +1,42 @@
+from __future__ import annotations
+
+import ctypes
+
+from datafusion import SessionContext, Table
+
+
+# Keep the backing memory alive for the lifetime of the module so the capsule
+# always wraps a valid (non-null) pointer. The capsule content is irrelevant for
+# this regression example—we only need a non-null address.
+_DUMMY_CAPSULE_BYTES = ctypes.create_string_buffer(b"x")
+
+class CapsuleContainer:
+    def __init__(self):
+        self.__datafusion_table_provider__ = make_table_provider_capsule
+
+def make_table_provider_capsule() -> object:
+    """Create a dummy PyCapsule with the expected table provider name."""
+
+    pycapsule_new = ctypes.pythonapi.PyCapsule_New
+    pycapsule_new.restype = ctypes.py_object
+    pycapsule_new.argtypes = [ctypes.c_void_p, ctypes.c_char_p, ctypes.c_void_p]
+    dummy_ptr = ctypes.cast(_DUMMY_CAPSULE_BYTES, ctypes.c_void_p)
+    return pycapsule_new(dummy_ptr, b"datafusion_table_provider", None)
+
+
+def main() -> None:
+    """Attempt to use the capsule the same way existing callers do."""
+
+    ctx = SessionContext()
+    try:
+        capsule = CapsuleContainer()
+    except Exception as err:
+        print("Creating the PyCapsule failed:", err)
+        return
+
+
+    ctx.read_table(capsule)
+    
+
+if __name__ == "__main__":
+    main()