Re: shelve crashing under Win ME

[gluckj]

OK, here's my workaround for shelve -- it's primitive and obviously
much slower (it saves the entire dictionary each time), and you have
to manually save -- BUT: it works...even on the Win ME machine. And
it's possibly more universally portable in the long run than
shelve...Also, once you open the dictionary, it is just as fast
(perhaps faster?) than shelve for reading the contents (just not for
saving...)
--Joel



#! /usr/local/bin/python
"""
myshelve.py -- a simpler (safer though slower) approach to shelve
"""

#Import Modules
import os, cPickle

def msopen(path):
""" open file containing pickled dict & return dict; if no such file,
create it & return empty dict """
if os.access(path, os.R_OK):
f=open(path, "r")
mydict=cPickle.load(f)
f.close()
return(mydict)
else:
f=open(path, "w")
cPickle.dump({}, f)
f.close()
return({})

def mssave(mydict,path):
""" pickle and save the dict to the file, overwriting previous
contents """
f=open(path, "w")
cPickle.dump(mydict, f)
f.close()

def mstest():
f1="_myshelvetest_.txt"
print "Testing myshelve..."
print "1) New file:",f1
if os.access(f1, os.F_OK): os.remove(f1)
d1=msopen(f1)
print "Contents of new file:",d1
d2=msopen(f1)
print "Contents on re-read:",d2
print "2) Write/Read/Overwrite/Read..."
d1={1:"hello",2:"there",3:"folks"}
print "Test dict:",d1
mssave(d1,f1)
d2=msopen(f1)
print "Loaded:",d2
print "Equal?",d1==d2
d1={1:"goodbye",2:"now",3:"folks"}
print "Test dict:",d1
mssave(d1,f1)
d2=msopen(f1)
print "Loaded:",d2
print "Equal?",d1==d2
print "** DONE **"
os.remove(f1)

if __name__=="__main__": mstest()



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Re: shelve crashing under Win ME

[gluckj]

Hi Jim,

Thanks for your messages -- however, py2exe is NOT the issue -- as you
can see with my example above, shelve is crashing even just by calling
it from IDLE (latest PC version of IDLE & Python), running on a Win ME
machine.

Anyone else out there having access to a Win ME PC willing to try it?
Thanks for checking!

In the meantime, I may replace shelve with a simpler workaround using
cPickle & basic flat file operations.

-- Joel
p.s. -- Jim, I too had to import dbhash in my program to make it work
using py2exe, so you are right on, there.

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shelve crashing under Win ME

[gluckj]

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 (r251:54863, Apr 18 2007, 08:51:08) [MSC
v.1310 32 bit (Intel)] on win32
IDLE 1.2.1
>>> import shelve
>>> f=shelve.open("foo")

Traceback (most recent call last):
  File "", line 1, in 
f=shelve.open("foo")
  File "C:\PYTHON25\lib\shelve.py", line 225, in open
return DbfilenameShelf(filename, flag, protocol,
writeback)
  File "C:\PYTHON25\lib\shelve.py", line 209, in
__init__
Shelf.__init__(self, anydbm.open(filename, flag),
protocol, writeback)
  File "C:\PYTHON25\lib\anydbm.py", line 83, in open
return mod.open(file, flag, mode)
  File "C:\PYTHON25\lib\dbhash.py", line 16, in open
return bsddb.hashopen(file, flag, mode)
  File "C:\PYTHON25\lib\bsddb\__init__.py", line 306,
in hashopen
d.open(file, db.DB_HASH, flags, mode)
DBError: (5, 'Input/output error')
>>>

For those who know shelve, this should actually run fine (if the file
"foo" does not exist it should create it). Printing the value of "f"
should show an empty dictionary {}.

It does run fine on my iBook (under Python 2.4.4) and on my iBook's
Virtual PC running Win XP & Python 2.5.0. I do not think this is a
Python 2.5.1 problem, because my first attempt to run my program on
the Win ME machine was with a version of the program I ported using
Py2exe on the VPC under Python 2.5.0, and it crashed the same way when
run on the Win ME machine (I subsequently installed Python on the Win
ME PC to try to get to the root of the problem.)

Help! How do I get Win ME (or at least the misbehaving Win ME machine
in my office) to run shelve? (or more specifically run bsddb's
hashopen?)

Or should I trash shelve entirely and rewrite all my code to use a
simpler, homemade database scheme?

Thanks for any advice!

Warmly,
Joel
[EMAIL PROTECTED]

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