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# SafeWriteFile.py
#
# This file is a writable file object. It writes to a specified newname,
# and when closed, renames the file to the realname. If the object is
# deleted, without being closed, this rename isn't done. If abort() is
# called, it also disables the rename.
#
# Copyright 2001 Adam Heath <doogie@debian.org>
#
# This file is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
from types import StringType
from shutil import copy2
from string import find
from os import rename
class ObjectNotAllowed(Exception):
pass
class InvalidMode(Exception):
pass
class SafeWriteFile:
def __init__(self, newname, realname, mode="w", bufsize=-1):
if type(newname)!=StringType:
raise ObjectNotAllowed(newname)
if type(realname)!=StringType:
raise ObjectNotAllowed(realname)
if find(mode, "r")>=0:
raise InvalidMode(mode)
if find(mode, "a")>=0 or find(mode, "+") >= 0:
copy2(realname, newname)
self.fobj=open(newname, mode, bufsize)
self.newname=newname
self.realname=realname
self.__abort=0
def close(self):
self.fobj.close()
if not (self.closed and self.__abort):
rename(self.newname, self.realname)
def abort(self):
self.__abort=1
def __del__(self):
self.abort()
del self.fobj
def __getattr__(self, attr):
try:
return self.__dict__[attr]
except:
return eval("self.fobj." + attr)
if __name__ == "__main__":
import time
f=SafeWriteFile("sf.new", "sf.data")
f.write("test\n")
f.flush()
time.sleep(1)
f.close()
# vim:ts=4:sw=4:et:
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