"""Script demonstrating close regression with weakref change

Prints nothing on earlier versions, but with Python 2.7 outputs similar to:
    Error in atexit._run_exitfuncs:
    Traceback (most recent call last):
      File "python-trunk/lib/atexit.py", line 24, in _run_exitfuncs
        func(*targs, **kargs)
      File "python-trunk/lib/logging/__init__.py", line 1615, in shutdown
        h.flush()
      File "python-trunk/lib/logging/__init__.py", line 824, in flush
        self.stream.flush()
    ValueError: I/O operation on closed file
    Error in sys.exitfunc:
    Traceback (most recent call last):
      File "python-trunk/lib/atexit.py", line 24, in _run_exitfuncs
        func(*targs, **kargs)
      File "python-trunk/lib/logging/__init__.py", line 1615, in shutdown
        h.flush()
      File "python-trunk/lib/logging/__init__.py", line 824, in flush
        self.stream.flush()
    ValueError: I/O operation on closed file
"""
import os, atexit

_ref_list = []
# Keep this list alive till the atexit function runs
atexit.register(lambda _=_ref_list: None)

import logging

def register_handler():
    """Create, add, remove, and close a handler, and return it"""
    f = open(os.devnull, "w")
    handler = logging.StreamHandler(f)
    logger = logging.getLogger("test")
    logger.addHandler(handler)
    logger.removeHandler(handler)
    # Closing the handler now does nothing in Python 2.7 so...
    handler.close()
    # ...closing the underlying file is now unsafe
    f.close()
    return handler

if __name__ == "__main__":
    # Reference held anywhere that outlives logging atexit shutdown
    _ref_list.append(register_handler())