[Tutor] Re: using IDLE and changing variables

Christopher Smith csmith@blakeschool.org
Sat, 04 Aug 2001 20:04:09 -0500

alan.gauld@bt.com writes:
>> Let's say at one point you had a variable x defined 
>> and you used it in several places.  Then you change 
>> the variable from x to y but forget to change it 
>> everywhere.  
>That'd be a programmer error in every environment I've 
>ever used. Some language compilers will tell you if you 
>remove the original declaration/definition of the variable 
>(x in your case) and then try to use it. Python will 
>warn you in some situations. But it has nothing to do 
>with IDLE per se, it's all to do with Python itself.

(Sorry, I meant IDE.)
Yes, I realize that it's an error on the programmer's
part, but Python usually knows enough to warn you.  The
reason I suggested that it was an IDE error is that
if it purged memory before running a script that you are
working on it woud realize that an error was occuring.
Here's a really simple demonstration of what I mean:

#new script
print x

(when you run this you see "2" printed in the output window.)

print x

You still see "2" printed in the output window.

>> I guess what I'm looking for is something like BASIC's "new" 
>> command that flushes out everything of the session and begins 
>> fresh.
>The interactive prompt doesn't have that feature but 
>working in IDLE the best thing IMHO is simply to create 
>a new file using File|New...

Yes, I see that's a good approach.  It appears that
each user created script window and the interactive window
keep track of their own variables and modules.