[Tutor] Fwd: pickle module error in source code
Hi! My name is Shreya Marwaha. I’m class 12th student in India. I’m using
2.7.5 python version [MSC v.1500 64 bit (AMD64)] on win32 as instructed by
CBSE (central board of secondary education). I’ve been having problem in
using pickle module. It keeps on showing error in the source code. I’ve
attached two files: 1. Prax.py file with error1.txt 2. Video.py file
with error.txt Prax.py file is a simple problem, the first program I
tried with pickle module. Video.py is my project which I’ll be submitting
at the end of my year at school i.e. February 2015. I’ve attached two text
documents in which both are showing the error occurring in both the
problems. The errors in both the programs are similar. Please help me in
this context. -Shreya Marwaha
# File name: ...\\Source_XII\Project\Video.py
import os
from pickle import load, dump
import datetime
import string
MFile = Master.dat
File1 = Cassettes.dat
File2 = Balance.dat
File3 = Customer.dat
Cdate = datetime.datetime.now() # Current date and time
# Class for date
class Cast_Date:
def __init__(self):
self.dd = Cdate.day
self.mm = Cdate.month
self.yy = Cdate.year
class Master:
# Constructor
def __init__(self):
self.Cast_Code = 0 # cassette/CD code - (Like, 1, 2, 3, etc.)
self.Cast_Name = # Title of the cassette/CD
self.Cast_Comp = # cassette/CD company
self.Cast_Price = 0 # Price per cassette/CD
def Check_Code(self, C_Code):
MList = list()
TRec = list()
Flag = False # To check if Cast_Code is in Master.dat or not
if os.path.isfile(MFile):
Mobj = open(MFile, 'rb')
try:
while True:
MRec = [] # For extracting Master.dat records
MRec = load(Mobj)
if (C_Code == MRec[0]):
TRec = MRec
MList.append(MRec[0])
except EOFError:
pass
for i in range(len(MList)):
if (C_Code == MList[i]):
Flag = True
break
Mobj.close()
# Flag for Master data entry and TRec for Cassette data entry
return Flag, TRec
# For Master data entry
def Master_Entry(self):
TRec = list() # A temporary list to store master record
print(Add Master Cassette/CD);
ch ='Y'
while ch=='Y':
while True:
self.Cast_Code = int(input(Cassette/CD Code (1/2/3...) # ))
Flag, TRec = self.Check_Code(self.Cast_Code)
if (Flag == False):
while True:
self.Cast_Name = input(Cassette/CD Name : )
if (self.Cast_Name == 0 or len(self.Cast_Name) 25):
print(Cassette/CD Name should not greater than 25)
else:
break
while True:
self.Cast_Comp = input(Company Name : )
if (self.Cast_Comp == 0 or len(self.Cast_Comp) 25):
print(Company Name should not greater than 25)
else:
break
while True:
self.Cast_Price = float(input(Individual Cassette/CD
price : ))
if (self.Cast_Price = 0):
print(Enter valid price for Cassette/CD)
else:
break;
with open(MFile, 'ab+') as Mobj:
if not Mobj:
print (MFile, does not created)
else:
# Appends data into a sequnce object
MList = list()
MList.append(self.Cast_Code)
MList.append(self.Cast_Name)
MList.append(self.Cast_Comp)
MList.append(self.Cast_Price)
# Write data into binary file
dump(MList, Mobj)
else:
print (Code, self.Cast_Code, is already in 'Master.dat'
file)
ch = input(Add new Cassette/CD code? Y/N: )
ch = ch.upper()
if ch=='Y':
continue
else:
break
def Master_Display(self):
if not os.path.isfile(MFile):
print (MFile, file does not exist)
else:
Mobj = open(MFile, 'rb')
print (\nCassette/CD Master Report)
print (= * 25)
print ({0:7} {1:30} {2:20} {3:8}.format( Code, Cassette/CD
Name, Company Name, Price))
print (- * 70)
Re: [Tutor] Fwd: pickle module error in source code
On 01/01/15 14:06, Vedhi Shreya Marwaha wrote:
Hi! My name is Shreya Marwaha. I’m class 12th student in India. I’m using
2.7.5 python version [MSC v.1500 64 bit (AMD64)] on win32 as instructed by
CBSE (central board of secondary education). I’ve been having problem in
using pickle module.
OK, welcome.
It keeps on showing error in the source code. I’ve
attached two files
If the files are short its better to just paste the contents
into your mail. Not everyone can (or is allowed to) read
attachments.
: 1. Prax.py file with error1.txt 2. Video.py file
with error.txt Prax.py file is a simple problem, the first program I
tried with pickle module.
OK, Let's stick with that initially.
The error says:
Traceback (most recent call last):
File C:\Users\Home\Downloads\prax.py, line 25, in module
a=pickle.load(f)
File C:\Python27\lib\pickle.py, line 1378, in load
return Unpickler(file).load()
File C:\Python27\lib\pickle.py, line 858, in load
dispatch[key](self)
File C:\Python27\lib\pickle.py, line 880, in load_eof
raise EOFError
EOFError
The relevant code is:
import pickle
a=student()
f=open(student.log,wb+)
In general, don;t use the + modifier with files. It usually creates more
confusion. Just open the file for reading after you finish
writing. And try very hard not to mix reading and writing to the same file.
a.input()
pickle.dump(a,f)
Here you have written your data to the file.
The file 'cursor' is now pointing at the end of the file.
a=pickle.load(f)
Here you try to read from the file but the cursor is already
at the end, so you get an end of file error. To make it work
you could rewind the cursor to the beginning of the file
using seek(). But it would be much safer to simply close
the file after the dump() and then reopen the file for
reading. That avoids a whole bunch of potential complexity
and bugs just waiting to bite.
Also, consider using the 'with' structure for handling
files, it is generally safer than open/close:
with open('student.log','wb') as f:
a.input()
pickle.dump(a,f)
with open('student.log','rb') as f:
a = pickle.load()
'with' ensures the files are closed after use.
HTH
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos
___
Tutor maillist - Tutor@python.org
To unsubscribe or change subscription options:
https://mail.python.org/mailman/listinfo/tutor
