Raise exception when open with write mode in call stack

cloudpathlib/cloudpath.py

@@ -4,11 +4,14 @@
 import fnmatch
 import os
 from pathlib import Path, PosixPath, PurePosixPath, WindowsPath
+import inspect
+import traceback
 from typing import Any, IO, Iterable, Optional, TYPE_CHECKING, Union
 from urllib.parse import urlparse
 from warnings import warn
 
 from .exceptions import (
+    BuiltInOpenWriteError,
     ClientMismatchError,
     CloudPathFileExistsError,
     CloudPathIsADirectoryError,
@@ -205,6 +208,19 @@ def __eq__(self, other: Any) -> bool:
         return isinstance(other, type(self)) and str(self) == str(other)
 
     def __fspath__(self):
+        WRITE_MODES = {"r+", "w", "w+", "a", "a+", "rb+", "wb", "wb+", "ab", "ab+"}
+        for frame, _ in traceback.walk_stack(None):
+            if "open" in frame.f_code.co_names:
+                code_context = inspect.getframeinfo(frame).code_context
+                if "open(" in code_context[0]:
+                    for mode in WRITE_MODES:
+                        if f'"{mode}"' in code_context[0] or f"'{mode}'" in code_context[0]:
+                            raise BuiltInOpenWriteError(
+                                "Detected the use of built-in open function with a cloud path and write mode. "
+                                "Cloud paths do not support the open function in write mode; "
+                                "please use the .open() method instead."
+                            )
+
         if self.is_file():
             self._refresh_cache(force_overwrite_from_cloud=False)
         return str(self._local)

cloudpathlib/exceptions.py

@@ -12,6 +12,10 @@ class AnyPathTypeError(CloudPathException, TypeError):
     pass
 
 
+class BuiltInOpenWriteError(CloudPathException):
+    pass
+
+
 class ClientMismatchError(CloudPathException, ValueError):
     pass
 

tests/test_cloudpath_file_io.py

@@ -5,7 +5,11 @@
 
 import pytest
 
-from cloudpathlib.exceptions import CloudPathIsADirectoryError, DirectoryNotEmptyError
+from cloudpathlib.exceptions import (
+    BuiltInOpenWriteError,
+    CloudPathIsADirectoryError,
+    DirectoryNotEmptyError,
+)
 
 
 def test_file_discovery(rig):
@@ -113,3 +117,26 @@ def test_os_open(rig):
     p = rig.create_cloud_path("dir_0/file0_0.txt")
     with open(p, "r") as f:
         assert f.readable()
+
+    with pytest.raises(BuiltInOpenWriteError):
+        with open(p, "w") as f:
+            pass
+
+    with pytest.raises(BuiltInOpenWriteError):
+        with open(p, "wb") as f:
+            pass
+
+    with pytest.raises(BuiltInOpenWriteError):
+        with open(p, "a") as f:
+            pass
+
+    with pytest.raises(BuiltInOpenWriteError):
+        with open(p, "r+") as f:
+            pass
+
+    # with pytest.raises(BuiltInOpenWriteError):
+    #     with open(
+    #         p,
+    #         "w",
+    #     ) as f:
+    #         pass