patch_attrs helper

src/compressed_tensors/utils/helpers.py

@@ -44,6 +44,7 @@
     "pack_bitmasks",
     "unpack_bitmasks",
     "patch_attr",
+    "patch_attrs",
     "ParameterizedDefaultDict",
     "get_num_attn_heads",
     "get_num_kv_heads",
@@ -368,6 +369,43 @@ def patch_attr(base: object, attr: str, value: Any):
             delattr(base, attr)
 
 
+@contextlib.contextmanager
+def patch_attrs(bases: list[object], attr: str, values: list[Any]):
+    """
+    Same as `patch_attr` but for a list of objects to patch
+    Patch attribute for a list of objects with list of values.
+    Original values are restored upon exit
+
+    :param bases: objects which has the attribute to patch
+    :param attr: name of the the attribute to patch
+    :param values: used to replace original values. Must be same
+        length as bases
+
+    Usage:
+    >>> from types import SimpleNamespace
+    >>> obj1 = SimpleNamespace()
+    >>> obj2 = SimpleNamespace()
+    >>> with patch_attr([obj1, obj2], "attribute", ["value1", "value2"]):
+    ...     assert obj1.attribute == "value1"
+    ...     assert obj2.attribute == "value2"
+    >>> assert not hasattr(obj1, "attribute")
+    >>> assert not hasattr(obj2, "attribute")
+    """
+    _sentinel = object()
+    original_values = [getattr(base, attr, _sentinel) for base in bases]
+
+    for base, value in zip(bases, values):
+        setattr(base, attr, value)
+    try:
+        yield
+    finally:
+        for base, original_value in zip(bases, original_values):
+            if original_value is not _sentinel:
+                setattr(base, attr, original_value)
+            else:
+                delattr(base, attr)
+
+
 class ParameterizedDefaultDict(dict):
     """
     Similar to `collections.DefaultDict`, but upon fetching a key which is missing,

tests/test_utils/test_helpers.py

@@ -21,6 +21,7 @@
     ParameterizedDefaultDict,
     load_compressed,
     patch_attr,
+    patch_attrs,
     save_compressed,
     save_compressed_model,
 )
@@ -176,6 +177,23 @@ def test_patch_attr():
     assert not hasattr(obj, "attribute")
 
 
+def test_patch_attrs():
+    num_objs = 4
+    objs = [SimpleNamespace() for _ in range(num_objs)]
+    for idx, obj in enumerate(objs):
+        if idx % 2 == 0:
+            obj.attribute = f"original_{idx}"
+    with patch_attrs(objs, "attribute", [f"patched_{idx}" for idx in range(num_objs)]):
+        for idx, obj in enumerate(objs):
+            assert obj.attribute == f"patched_{idx}"
+            obj.attribute = "modified"
+    for idx, obj in enumerate(objs):
+        if idx % 2 == 0:
+            assert obj.attribute == f"original_{idx}"
+        else:
+            assert not hasattr(obj, "attribute")
+
+
 def test_parameterized_default_dict():
     def add_one(value):
         return value + 1