473,836 Members | 1,457 Online
Bytes | Software Development & Data Engineering Community
+ Post

Home Posts Topics Members FAQ

shelve problem

Hi All,

Problem: Shelve module doesn't like me

OS: Win2000
version: 2.3.3

Here is simple reproduction code and the error that occurs:

import shelve, anydbm
test = shelve.open('he llo', 'r') # file hello does not exist
pass # this is called as hello does not exist

Exception exceptions.Attr ibuteError: "DbfilenameShel f instance has no
attribute 'writeback'" in

'__main__', line 7: pass
'shelve'.__del_ _(), line 148: self.close()
'shelve'.close( ), line 140: self.sync() 'shelve'.sync, line 151: if self.writeback and self.cache:

Forgive me if this query is obvious but I have searched mailing lists
and google but could not resolve the issue.

Speculative Analysis:

shelve.open calls the DbfilenameShelf constructor passing the filename

The DbfilenameShelf constructor does the following:

def __init__(self, filename, flag='c', protocol=None,
writeback=False , binary=None):
import anydbm
Shelf.__init__( self, anydbm.open(fil ename, flag), protocol,
writeback, binary)

The function anydbm.open throws an exception because:
1. the filename does not exist
2. the flag does not not contain a 'c' or an 'n'
(See anydbm.py line 77)

As the file "hello" does not exist the exception is thrown and caught
in my code.

I presume that python constructs the DbfilenameShelf object but does
not construct the parent shelf object because of that exception.

Then when python is cleaning up it destructs the DbfilenameShelf
object which I presume calls the destructor of the parent shelf
object. As the shelf object was not created due to initial exception,
python could not see the attributes and hence the Attribute Error

Comments Anyone?

Any questions please do not hesitate to contact me.

Jul 18 '05 #1
0 1370

This thread has been closed and replies have been disabled. Please start a new discussion.

Similar topics

by: Rami A. Kishek | last post by:
Hi - this mysterious behavior with shelve is just about to kill me. I hope someone here can shed some light. First of all, I have this piece of code which uses shelve to save instances of some class I define. It works perfectly on an old machine (PII-400) running Python 2.2.1 under RedHat Linux 8.0. When I try to run it under Python for windows ME on a P-4 1.4 GHz, however, it keeps crashing on reading from the shelved file the second...
by: seth | last post by:
Last week I encountered an AttributeError in my unit tests that I wasn'table to catch with an "except AttributeError" statement. The problem stemmed from a class that raised an error inside __init__and defined a __del__ method to clean up resources. I then discovered asimilar problem in the shelve module. This led me to two importantdiscoveries: 1. Attributes defined in __init__ after an error is raised will not be apart of the...
by: ex laguna | last post by:
Hi, I have ran into a problem with py2exe 0.5.0 and shelve in python 2.3.3. The script works fine standalone, but not with py2exe. Does anyone have a solution of workaround for this? Thanks much. # Begin of setup.py from distutils.core import setup import py2exe setup(console=)
by: Ray O | last post by:
I have read a number of threads relating to problems with shelve, but I couldn't find one directly related my experience, so I would appreciate some advice. The closest one ended with a recommendation to upgrade to Python 2.3, but that, unfortunately, is out of my control. The system I use runs Python 2.2.2, and whichdb gives dbhash. The problem only occurs when serializing class instances; lists don't seem to be affected. Every time...
by: Philippe C. Martin | last post by:
Hi, I just installed (compiled) Python 2.4.2 under Suse 10. The following code generates a seg error: import shelve print shelve.open ('test') I assume this has to do with the db behind shelve.
by: Michele Petrazzo | last post by:
Hi, I'm trying a script on a debian 3.1 that has problems on shelve library. The same script work well on a fedora 2 and I don't know why it create this problem on debian: #extract from my code import shelve class XX: def __init__(self): self._data = shelve.open("/tmp/myfile")
by: aomighty | last post by:
I wanted to write the following code: import shelve try: db = shelve.open(file, "r") except SomeError: print "Oh no, db not found" Only, I'm not sure what SomeError should be. I tried error, anydbm.error, shelve.open.anydb.error, etc. but can't find it. Things
by: gluckj | last post by:
Hi, I'm not a Win ME fan myself (I'm a Mac user), but I'm here in Thailand developing software for special-needs kids, and the test PC in my home office is a Win ME machine (sigh). So when I ported my Python program today to the PC, it quickly crashed. Everything seems to work except for shelve. Using the latest version of Python (2.5.1), when I do the following in IDLE on the Win ME machine here's the result: Python 2.5.1...
by: Matthew Schibler | last post by:
I'm a newbie to Python, with some experience using perl (where I used nested arrays and hashes extensively). I am building a script in python for a MUD I play, and I want to use the shelve module to store persistent information between script executions. The following code does not work for me, import shelve, sys, os, string db = shelve.open(os.path.abspath(os.path.dirname(sys.argv)) + '/' + 'sandbox.dat', 'c') db = 'apple'
by: marktang | last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look ! Part I. Meaning of...
by: Hystou | last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can effortlessly switch the default language on Windows 10 without reinstalling. I'll walk you through it. First, let's disable language synchronization. With a Microsoft account, language settings sync across devices. To prevent any complications,...
by: jinu1996 | last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth. The Art of Business Website Design Your website is...
by: agi2029 | last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own.... Now, this would greatly impact the work of software developers. The idea...
by: isladogs | last post by:
The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM). In this session, we are pleased to welcome a new presenter, Adolph Dupré who will be discussing some powerful techniques for using class modules. He will explain when you may want to use classes instead of User Defined Types (UDT). For example, to manage the data in unbound forms. Adolph will...
by: conductexam | last post by:
I have .net C# application in which I am extracting data from word file and save it in database particularly. To store word all data as it is I am converting the whole word file firstly in HTML and then checking html paragraph one by one. At the time of converting from word file to html my equations which are in the word document file was convert into image. Globals.ThisAddIn.Application.ActiveDocument.Select();...
by: 6302768590 | last post by:
Hai team i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system
by: muto222 | last post by:
How can i add a mobile payment intergratation into php mysql website.
by: bsmnconsultancy | last post by:
In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating effective websites that not only look great but also perform exceptionally well. In this comprehensive...

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.