This allows using a "with statement" together with instances of
atomic_ofstream. Allowing for more readable, less error prone and
shorter code.

Signed-off-by: Florian Schmaus <>
 lib/portage/util/ | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/lib/portage/util/ b/lib/portage/util/
index 0412b2b5911f..bedcbcfe6fcc 100644
--- a/lib/portage/util/
+++ b/lib/portage/util/
@@ -11,6 +11,7 @@ __all__ = ['apply_permissions', 'apply_recursive_permissions',
        'stack_dicts', 'stack_lists', 'unique_array', 'unique_everseen', 
        'write_atomic', 'writedict', 'writemsg', 'writemsg_level', 
+from contextlib import AbstractContextManager
 from copy import deepcopy
 import errno
 import io
@@ -1246,7 +1247,7 @@ def apply_secpass_permissions(filename, uid=-1, gid=-1, 
mode=-1, mask=-1,
                stat_cached=stat_cached, follow_links=follow_links)
        return all_applied
-class atomic_ofstream(ObjectProxy):
+class atomic_ofstream(AbstractContextManager, ObjectProxy):
        """Write a file atomically via os.rename().  Atomic replacement prevents
        interprocess interference and prevents corruption of the target
        file when the write is interrupted (for example, when an 'out of space'
@@ -1287,6 +1288,13 @@ class atomic_ofstream(ObjectProxy):
                                encoding=_encodings['fs'], errors='strict'),
                                mode=mode, **kargs))
+       def __exit__(self, exc_type, exc_val, exc_tb):
+               if exc_type is not None:
+                       self.abort()
+               else:
+                       self.close()
+               return None
        def _get_target(self):
                return object.__getattribute__(self, '_file')

Reply via email to