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Sun Apr 5 00:35:32 CEST 2009 · https://mail.python.org/pipermail/python-dev/2009-April/088212.html

Hey,

I noticed that the call pattern of the C-implemented io libraries is as
follows (translating from C to Python):

class _FileIO(object):
  def flush(self):
    if self.__IOBase_closed:
      raise ...

  def close(self):
    self.flush()
    self.__IOBase_closed = True

class _RawIOBase(_FileIO):
  def close(self):
    # do close
    _FileIO.close(self)

This means that, if a subclass overrides flush(), it will be called after
the file has been closed e.g.

>>> import io
>>> class MyIO(io.FileIO):
...     def flush(self):
...             print('closed:', self.closed)
...
>>> f = MyIO('test.out', 'wb')
>>> f.close()
closed: True

It seems to me that, during close, calls should only propagate up the
class hierarchy i.e.

class _FileIO(object):
  def flush(self):
    if self.__IOBase_closed:
      raise ...

  def close(self):
    _FileIO.flush(self)
    self.__IOBase_closed = True

I volunteer to change this if there is agreement that this is the way to go.

Cheers,
Brian

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[Python-Dev] Possible py3k io wierdness