#!/usr/bin/env python

# -*- coding: utf-8 -*-

"""

*TL;DR

Encapsulates all information needed to perform an action or trigger an event.

*Examples in Python ecosystem:

Django HttpRequest (without `execute` method):

https://docs.djangoproject.com/en/2.1/ref/request-response/#httprequest-objects

"""

from __future__ import print_function

import os

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(u"renaming %s to %s" % (src, dest))

os.rename(src, dest)

def main():

"""

>>> from os.path import lexists

>>> command_stack = [

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

... 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")

# Create empty file

>>> open("foo.txt", "w").close()

# Commands can be executed later on

>>> for cmd in command_stack:

... cmd.execute()

renaming foo.txt to bar.txt

renaming bar.txt to baz.txt

# And can also be undone at will

>>> for cmd in reversed(command_stack):

... cmd.undo()

renaming baz.txt to bar.txt

renaming bar.txt to foo.txt

>>> os.unlink("foo.txt")

"""

if __name__ == "__main__":

import doctest

doctest.testmod()