Message153

I've tried to solve a problem using the pickle module. I had to save some
integer values in the range 0..255. But when reading the
values (which I intentionally wrote as binary) I sometimes got back wrong
values. 
(Dumping as non-binary works correctly, but that didn't solve my problem)

To find out which values are in error I wrote a little test script. It looks a
bit curious because I had to catch an exception.

Well, I found a different way to solve my problem, but I didn't find out, why it
doesn't work with pickle. 
I didn't find a bug report which explains this problem.

The test script runs without problems with Python 1.5.1 on Linux.

This is my test script:
-----------------------
import sys
import pickle
tmpfile = "/tmp/test.tmp"

def saveValue( value):
	f = open(tmpfile,"w")
	p = pickle.Pickler(f,1)
	p.dump(value)
	f.close()
	
def loadValue():
	f=open(tmpfile,"r")
	retVal =  pickle.Unpickler(f).load()
	f.close()
	return retVal

for x in range(256):
	try:
		saveValue(x)
	except:
		print "Exception caught: cannot save ", x
	else:
		try:
			y = loadValue()
		except:
			print "Exception caught: cannot load previously saved value", x
		else:
			if x != y:
				print "saved: ", x,
				print "loaded: ", y
		
-----------------------

This is the output on my system (Windows NT, JPython 1.1, pylib152e, Java 1.2.2
and Java 1.1.8):
-------------------------------------
Exception caught: cannot load previously saved value 10
saved:  13 loaded:  10
saved:  128 loaded:  63
saved:  129 loaded:  63
saved:  130 loaded:  63
saved:  131 loaded:  63
saved:  132 loaded:  63
saved:  133 loaded:  63
saved:  134 loaded:  63
saved:  135 loaded:  63
saved:  136 loaded:  63
saved:  137 loaded:  63
saved:  138 loaded:  63
saved:  139 loaded:  63
saved:  140 loaded:  63
saved:  141 loaded:  63
saved:  142 loaded:  63
saved:  143 loaded:  63
saved:  144 loaded:  63
saved:  145 loaded:  63
saved:  146 loaded:  63
saved:  147 loaded:  63
saved:  148 loaded:  63
saved:  149 loaded:  63
saved:  150 loaded:  63
saved:  151 loaded:  63
saved:  152 loaded:  63
saved:  153 loaded:  63
saved:  154 loaded:  63
saved:  155 loaded:  63
saved:  156 loaded:  63
saved:  157 loaded:  63
saved:  158 loaded:  63
saved:  159 loaded:  63
-----------------------