Omer Khalid wrote:
Hi Dave,
Thanks for your reply. I actually didn't cut and paste my code as it was
dispersed in different places, i typed the logic behind my code in the email
(and obiviously made some typos, indentations is some thing else) but my
real code does not have these problems as my application runs fine with out
errors...
Except that the line where i want to update the value doesn't get updated
and no exception is thrown. What's surprising for me is that i am doing the
same thing in hundreds of places in my 3k+ line code but by some reason this
part doesn't work...
As far as the global variables are concerned, i am using them in other
places too and didn't see any problems.
I think some thing else is going on here as the statement above and below my
modified lines get executed.
Is there a way in Python to debug memory address or to see where in memory
this object is stored, and is there a lock on it or else?
Thanks,
Omer
**************************************
On Wed, Jul 29, 2009 at 8:56 PM, Dave Angel <da...@ieee.org> wrote:
Omer Khalid wrote:
Hi,
I am having a very strange problem with modifying a variable in a list in
my
program. Here is the code:
# a list that contains dictionary objects
jobs = []
index=5
for each in range(index):
jobs.append({'v':0})
some_function(index):
if jobs[index]['v'] == 0:
# set it to 1
jobs[index]['v'] = 1
print "Set to 1"
else:
print "Already set to 1"
loop():
index=0
for each in range(len(jobs)):
some_function(index)
index +=1
Apparently, the jobs[index]['v'] never get updated in the some_function
but
the print statement afterwards get printed...
What's really surprising is that there are no errors or exceptions and my
my
program runs in a single thread...so i have been unable to explain this
behavior.
Any insight would be much appreciated!
Cheers
Omer
There are four things to fix before the program does anything much at all.
Two places you're missing the def, indentation is inconsistent, and you
never actually call either of the functions. The first three are syntax
errors, so presumably your cut/paste in your computer is broken.
Once I make those four corrections, I get the following output:
Set to 1
Set to 1
Set to 1
Set to 1
Set to 1
But you never said what you got, nor what you expected. That's certainly
what I'd expect. And if you make a second call to loop() in your outer
code, you get five copies of "Already set to 1"
BTW, there are a number of things that could be done better. The main one
I'll point out is that you shouldn't re-use a global variable 'index' as a
local with different meaning. As someone else pointed out, since the global
is a constant, making it all uppercase is the convention.
DaveA
(You top-posted, so your ,message is out of sequence. More and more
people are doing that in this list.)
++++ ...Except that the line where i want to update the value doesn't
get updated...
And what makes you think that? You never answered my question. What did you
expect for output, and what did you get? I got exactly what I expected, when I
ran it.
++++ ... Is there a way in Python to debug memory address or
++++ to see where in memory this object is stored, and
++++ is there a lock on it or else?
If there really were a bug in the language, you might need such a tool.
I use Komodo IDE as a debugger, but there was no need in this case.
Adding a few print statements might clear up your confusion, but since
you haven't spelled out what it is, I can't suggest where. How about if
you just add a print jobs at the beginning of some_function() ?
Then you could see things getting updated perfectly.
DaveA
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