def execute(self):

pass

def undo(self):

# TODO handle src parameter as path

def __init__(self, src ):

self.src = src

self.dest = "Copy_"+src

self.name = "Copy " + src

def execute(self):

self.copy(self.src, self.dest)

def undo(self):

print('remove {} '.format( self.dest))

os.remove( self.dest)

def copy(self , src,dest ):

print('copy {} to {}'.format(src, dest))

def __init__(self, src, dest):

self.src = src

self.dest = dest

self.name="Move "+src

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))

command_stack = []

# commands are just pushed into the command stack

command_stack.append(CopyFileCommand('foo1.txt'))

command_stack.append(CopyFileCommand('Copy_foo1.txt'))

command_stack.append(MoveFileCommand('foo.txt', 'bar.txt'))

command_stack.append(MoveFileCommand('bar.txt', 'baz.txt'))

names=["foo.txt","baz.txt","foo1.txt"]

for name in names:

try:

os.unlink(name)

except:

pass

finally:

pass

# 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") as src1: # Creating the file

src1.close()

with open("foo1.txt", "w") as src2: # Creating the file

src2.close()

# they can be executed later on

for cmd in command_stack:

print "******Executing "+cmd.name

cmd.execute()

# and can also be undone at will

for cmd in reversed(command_stack):

print "" \

"------Undo " + cmd.name

cmd.undo()

except :

#e = sys.exc_info()[0]

#print("Error: %s" % e)

exc_type, exc_value, exc_traceback = sys.exc_info()

print "*** print_tb:"

traceback.print_tb(exc_traceback, limit=1, file=sys.stdout)

print "*** print_exception:"

traceback.print_exception(exc_type, exc_value, exc_traceback,

limit=2, file=sys.stdout)

print "*** print_exc:"

traceback.print_exc()

print "*** format_exc, first and last line:"

formatted_lines = traceback.format_exc().splitlines()

print formatted_lines[0]

print formatted_lines[-1]

print "*** format_exception:"

print repr(traceback.format_exception(exc_type, exc_value,

exc_traceback))

print "*** extract_tb:"

print repr(traceback.extract_tb(exc_traceback))

print "*** format_tb:"

print repr(traceback.format_tb(exc_traceback))

print "*** tb_lineno:", exc_traceback.tb_lineno

finally:

print "finaly block "

os.unlink("foo.txt")