Refactor patching to specific submodule (#2639)

* Create patching submodule

* Minor fix in docstring section header

src/datasets/streaming.py

@@ -3,75 +3,13 @@
 from typing import Optional, Union
 
 from .utils.logging import get_logger
+from .utils.patching import patch_submodule
 from .utils.streaming_download_manager import xjoin, xopen
 
 
 logger = get_logger(__name__)
 
 
-class _PatchedModuleObj:
-    """Set all the modules components as attributes of the _PatchedModuleObj object"""
-
-    def __init__(self, module):
-        if module is not None:
-            for key in getattr(module, "__all__", module.__dict__):
-                if not key.startswith("__"):
-                    setattr(self, key, getattr(module, key))
-
-
-class patch_submodule:
-    """
-    Patch a submodule attribute of an object, by keeping all other submodules intact at all levels.
-
-    Example::
-
-        >>> import importlib
-        >>> from datasets.load import prepare_module
-        >>> from datasets.streaming import patch_submodule, xjoin
-        >>>
-        >>> snli_module_path, _ = prepare_module("snli")
-        >>> snli_module = importlib.import_module(snli_module_path)
-        >>> patcher = patch_submodule(snli_module, "os.path.join", xjoin)
-        >>> patcher.start()
-        >>> assert snli_module.os.path.join is xjoin
-    """
-
-    _active_patches = []
-
-    def __init__(self, obj, target: str, new):
-        self.obj = obj
-        self.target = target
-        self.new = new
-        self.key = target.split(".")[0]
-        self.original = getattr(obj, self.key, None)
-
-    def __enter__(self):
-        *submodules, attr = self.target.split(".")
-        current = self.obj
-        for key in submodules:
-            setattr(current, key, _PatchedModuleObj(getattr(current, key, None)))
-            current = getattr(current, key)
-        setattr(current, attr, self.new)
-
-    def __exit__(self, *exc_info):
-        setattr(self.obj, self.key, self.original)
-
-    def start(self):
-        """Activate a patch."""
-        self.__enter__()
-        self._active_patches.append(self)
-
-    def stop(self):
-        """Stop an active patch."""
-        try:
-            self._active_patches.remove(self)
-        except ValueError:
-            # If the patch hasn't been started this will fail
-            return None
-
-        return self.__exit__()
-
-
 def extend_module_for_streaming(module_path, use_auth_token: Optional[Union[str, bool]] = None):
     """
     Extend the `open` and `os.path.join` functions of the module to support data streaming.

src/datasets/utils/patching.py

@@ -0,0 +1,67 @@
+from .logging import get_logger
+
+
+logger = get_logger(__name__)
+
+
+class _PatchedModuleObj:
+    """Set all the modules components as attributes of the _PatchedModuleObj object."""
+
+    def __init__(self, module):
+        if module is not None:
+            for key in getattr(module, "__all__", module.__dict__):
+                if not key.startswith("__"):
+                    setattr(self, key, getattr(module, key))
+
+
+class patch_submodule:
+    """
+    Patch a submodule attribute of an object, by keeping all other submodules intact at all levels.
+
+    Examples:
+
+        >>> import importlib
+        >>> from datasets.load import prepare_module
+        >>> from datasets.streaming import patch_submodule, xjoin
+        >>>
+        >>> snli_module_path, _ = prepare_module("snli")
+        >>> snli_module = importlib.import_module(snli_module_path)
+        >>> patcher = patch_submodule(snli_module, "os.path.join", xjoin)
+        >>> patcher.start()
+        >>> assert snli_module.os.path.join is xjoin
+    """
+
+    _active_patches = []
+
+    def __init__(self, obj, target: str, new):
+        self.obj = obj
+        self.target = target
+        self.new = new
+        self.key = target.split(".")[0]
+        self.original = getattr(obj, self.key, None)
+
+    def __enter__(self):
+        *submodules, attr = self.target.split(".")
+        current = self.obj
+        for key in submodules:
+            setattr(current, key, _PatchedModuleObj(getattr(current, key, None)))
+            current = getattr(current, key)
+        setattr(current, attr, self.new)
+
+    def __exit__(self, *exc_info):
+        setattr(self.obj, self.key, self.original)
+
+    def start(self):
+        """Activate a patch."""
+        self.__enter__()
+        self._active_patches.append(self)
+
+    def stop(self):
+        """Stop an active patch."""
+        try:
+            self._active_patches.remove(self)
+        except ValueError:
+            # If the patch hasn't been started this will fail
+            return None
+
+        return self.__exit__()