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#!/usr/bin/env python
# -*- coding: utf-8 -*-
import os
from os.path import lexists
class MoveFileCommand(object):
def __init__(self, src, dest):
self.src = src
self.dest = dest
def execute(self):
self.rename(self.src, self.dest)
def undo(self):
self.rename(self.dest, self.src)
def rename(self, src, dest):
print('renaming {} to {}'.format(src, dest))
os.rename(src, dest)
def main():
command_stack = []
# commands are just pushed into the command stack
command_stack.append(MoveFileCommand('foo.txt', 'bar.txt'))
command_stack.append(MoveFileCommand('bar.txt', 'baz.txt'))
# verify that none of the target files exist
assert(not lexists("foo.txt"))
assert(not lexists("bar.txt"))
assert(not lexists("baz.txt"))
try:
with open("foo.txt", "w"): # Creating the file
pass
# they can be executed later on
for cmd in command_stack:
cmd.execute()
# and can also be undone at will
for cmd in reversed(command_stack):
cmd.undo()
finally:
os.unlink("foo.txt")
if __name__ == "__main__":
main()
### OUTPUT ###
# renaming foo.txt to bar.txt
# renaming bar.txt to baz.txt
# renaming baz.txt to bar.txt
# renaming bar.txt to foo.txt