Issue 2021: Allow NamedTemporaryFile and SpooledTemporaryFile to be used as context managers. (The NamedTemporaryFile fix should be considered for backporting to 2.5)
diff --git a/Lib/tempfile.py b/Lib/tempfile.py
index c0e34bc..e75c8fe 100644
--- a/Lib/tempfile.py
+++ b/Lib/tempfile.py
@@ -370,6 +370,7 @@
raise IOError, (_errno.EEXIST, "No usable temporary filename found")
+
class _TemporaryFileWrapper:
"""Temporary file wrapper
@@ -385,17 +386,25 @@
self.delete = delete
def __getattr__(self, name):
+ # Attribute lookups are delegated to the underlying file
+ # and cached for non-numeric results
+ # (i.e. methods are cached, closed and friends are not)
file = self.__dict__['file']
a = getattr(file, name)
- if type(a) != type(0):
+ if not issubclass(type(a), type(0)):
setattr(self, name, a)
return a
+ # The underlying __enter__ method returns the wrong object
+ # (self.file) so override it to return the wrapper
+ def __enter__(self):
+ self.file.__enter__()
+ return self
+
# NT provides delete-on-close as a primitive, so we don't need
# the wrapper to do anything special. We still use it so that
# file.name is useful (i.e. not "(fdopen)") with NamedTemporaryFile.
if _os.name != 'nt':
-
# Cache the unlinker so we don't get spurious errors at
# shutdown when the module-level "os" is None'd out. Note
# that this must be referenced as self.unlink, because the
@@ -413,6 +422,14 @@
def __del__(self):
self.close()
+ # Need to trap __exit__ as well to ensure the file gets
+ # deleted when used in a with statement
+ def __exit__(self, exc, value, tb):
+ result = self.file.__exit__(exc, value, tb)
+ self.close()
+ return result
+
+
def NamedTemporaryFile(mode='w+b', bufsize=-1, suffix="",
prefix=template, dir=None, delete=True):
"""Create and return a temporary file.
@@ -511,6 +528,20 @@
self._rolled = True
+ # The method caching trick from NamedTemporaryFile
+ # won't work here, because _file may change from a
+ # _StringIO instance to a real file. So we list
+ # all the methods directly.
+
+ # Context management protocol
+ def __enter__(self):
+ if self._file.closed:
+ raise ValueError("Cannot enter context with closed file")
+ return self
+
+ def __exit__(self, exc, value, tb):
+ self._file.close()
+
# file protocol
def __iter__(self):
return self._file.__iter__()