[Tutor] Formatting zip module arguments correctly

[Benjamin Serrato]

Please tell me why this code fails. I am new and I don't understand why my
formatting of my zip arguments is incorrect. Since I am unsure how to
communicate best so I will show the code, the error message, and what I
believe is happening.

#!c:\python30
# Filename: backup_ver5.py

import os
import time
import zipfile


source = r'C:\Documents and Settings\Benjamin Serrato\My
Documents\python\backup_list'

target_dir = r'C:\Documents and Settings\Benjamin Serrato\My
Documents\python\backup_dir'

today = target_dir + os.sep + time.strftime('%Y%m%d')

now = time.strftime('%H%M%S')

comment = input('Enter a comment --> ')

if len(comment) == 0:
	target = today + os.sep + now + '.zip'
else:
	target = today + os.sep + now + '_' + \
	comment.replace(' ', '_') + '.zip'

if not os.path.exists(today):
	os.mkdir(today)
	print('Successfully created directory', today)


print(target)
print(source)
zip_command = zipfile.ZipFile(target, 'w').write(source)

if os.system(zip_command) == 0:
	print('Successful backup to', target)
else:
	print('Backup FAILED')

I receive this error message:

Enter a comment -->
C:\Documents and Settings\Benjamin Serrato\My
Documents\python\backup_dir\200904
05\154956.zip
C:\Documents and Settings\Benjamin Serrato\My Documents\python\backup_list
Traceback (most recent call last):
  File "C:\Documents and Settings\Benjamin Serrato\My
Documents\python\backup_ve
r5.py", line 32, in <module>
    zip_command = zipfile.ZipFile(target, 'w').write(source)
  File "c:\python30\lib\zipfile.py", line 1031, in write
    fp = io.open(filename, "rb")
  File "C:\Python30\lib\io.py", line 222, in open
    closefd)
  File "C:\Python30\lib\io.py", line 615, in __init__
    _fileio._FileIO.__init__(self, name, mode, closefd)
IOError: [Errno 13] Permission denied: 'C:\\Documents and Settings\\Benjamin
Ser
rato\\My Documents\\python\\backup_list'

The two print tests before zip_command is assigned tell me that the two
strings are being passed to zipfile.ZipFile() correctly. The traceback tells
me I am not calling zipfile.ZipFile() correctly. The error in __init__ makes
me more sure of this. Last, the problem seems to be that I am causing my
path string to have double backslashes. I can't follow why the IOError shows
that.

I used this site <http://docs.python.org/dev/3.0/library/zipfile.html> to
figure out how to use zipfile. zipfile is a class, I import it at the start
of the program then I use it and its primary method. I pass the file I would
like to write to zipfile.ZipFile('file to write', 'mode') and set the
program to open an object set to be writable. Then the command writes the
file to the destination folder with a sub-method like so, "".zipfile('files
to write').

Where am I going wrong?
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