ENH: backport cbook._setattr_cm

anntzer · tacaswell · commit 42bd99abbcf9 · 2018-08-04T20:11:32.000-04:00
This context manager was added to master in 690b213 via matplotlib#10314. We do not want to backport that entire commit, however the backport of matplotlib#11407 requires this context manger. It is private and self contained to low-risk to backport
diff --git a/lib/matplotlib/cbook/__init__.py b/lib/matplotlib/cbook/__init__.py
@@ -2832,3 +2832,21 @@ def _str_lower_equal(obj, s):
     cannot be used in a boolean context.
     """
     return isinstance(obj, six.string_types) and obj.lower() == s
+
+
+@contextlib.contextmanager
+def _setattr_cm(obj, **kwargs):
+    """Temporarily set some attributes; restore original state at context exit.
+    """
+    sentinel = object()
+    origs = [(attr, getattr(obj, attr, sentinel)) for attr in kwargs]
+    try:
+        for attr, val in kwargs.items():
+            setattr(obj, attr, val)
+        yield
+    finally:
+        for attr, orig in origs:
+            if orig is sentinel:
+                delattr(obj, attr)
+            else:
+                setattr(obj, attr, orig)
