Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[alway]

In c++, global variables are file scope by default. But you can use 'extern' in other files to put that variable in that file's scope as well.
Which would be bad if you had 3 files:
File1:
int FUBAR;
File2:
int FUBAR;
File3:
extern int FUBAR;

SUDDENLY, LINKER ERRORS. And if you happen to be working on a project with a dozen other coders, all of whom are using global variables, that could get messy. Or it could be even worse:
File1: //implemented by programmer A
int FUBAR;
File2: //was going to be implemented by programmer B before he forgot
File 3: //implemented by programmer B
extern int FUBAR;
No compile errors, but you are now referencing some other variable the other guy put in. Which breaks everything.

Though that isn't really the main reason. It's mostly because you lose any ability to have centrallized control over the variable. Now anyone, anywhere can access your variable. And the only way to figure out where they are using it is Ctrl+F the entire project.

[Dutchling]

Running this function:

Code: [Select]

def loop(typed=None):
    while typed != 'q': #<= line 7 in simple.py
    <rest>Gives me this error:

Message   File Name   Line   Position   
Traceback            
    <module>   C:\Users\s4197887.RU\Downloads\Families\Families\families.py   39      
    main   C:\Users\s4197887.RU\Downloads\Families\Families\families.py   37      
    loop   C:\Users\s4197887.RU\Downloads\Families\Families\simple.py   7      
UnboundLocalError: local variable 'typed' referenced before assignment            

How is this possible? This even happens if I start the function with 'typed = None'.

[Max White]

Well that is weird.
I just tested the following

Code: [Select]

def foo(bar = None):
    if (bar is None):
        print "Bar is None"
    else:
        print bar
And it works fine.
Can I see how you are trying to call the method?

[Dutchling]

Code: [Select]

# families.py
import simple

def main(years):
    <unrelated stuff>
    simple.loop()

[Max White]

Interesting.
Try running just your simple module in the Python Shell, and typing in loop(), see what it spits out.

EDIT:
Ok like 10% chance this will fix your problem. Worse than last time I had a hunch, but worth a shot!

Code: [Select]

while (typed != 'q'):

I'm pretty sure Python is meant to be smarter than that, but who knows.

[Dutchling]

Hmm, the program (families.py)actually works using Python Shell, I am using portable PyScripter btw, as I am at my uni.
Is there a way to make Python Shell accept string using 'x = input()'? As it still crashes, but now because of that.

edit: PyScripter does work when just calling loop() from simple.py. Odd.

[olemars]

Do you assign to typed further down in the function?

[Dutchling]

Yes, but only using input() , and it crashes before that.

[olemars]

I'm extremely rusty on python, but it could be a scope issue due to that assignment. Try commenting it out?

[Max White]

It is getting too late at night to be doing python. The language just gives you waaay too much rope to hang yourself!
Clearly there is a problem with your main somehow, otherwise it would also give that error when calling just that method. Pot shot time? Sure, why not. Fuck you proper testing methods!

1% chance to to cause: Do you use typed anywhere outside of the loop method?

[Dutchling]

Well, the error is probably just because of the portable PyScripter I am using, as Python Shell doesn't crash.
Well, it does crash, but only after the whole typed stuff, so it's not that. Is there a way to actually see the error message? Shell closes too fast for me to read it >.>

[Nadaka]

Well, the error is probably just because of the portable PyScripter I am using, as Python Shell doesn't crash.
Well, it does crash, but only after the whole typed stuff, so it's not that. Is there a way to actually see the error message? Shell closes too fast for me to read it >.>

open the shell first. then run your program. the shell and its output should remain open when the program errors out.

[Max White]

Well, the error is probably just because of the portable PyScripter I am using, as Python Shell doesn't crash.
Well, it does crash, but only after the whole typed stuff, so it's not that. Is there a way to actually see the error message? Shell closes too fast for me to read it >.>

Oh ok. Wait, your shell closes?
You mean the thing that looks like this?

Spoiler (click to show/hide)

[Dutchling]

Wait, I thought that was IDLE? I meant the thing that looks like this:

Spoiler (click to show/hide)

I can't actually use IDLE right now, as I am at my uni.

And the problem has been fixed, I have no idea why, as the exact code which causes errors earlier on now works.

[Max White]

Now I could be making a fool of myself, but I'm oretty sure that the Command line and the IDLE are both shells.
Also, why would your school not have it? Seriously??!!?? Have you checked? It should be there!