namespaces, scoping and variables

[Chris Hare]

Thanks to everyone for answering my question.  I think its clear now.  I'll just go the "stuff 'em in a module and import that" route.

Chris

On Aug 2, 2010, at 3:03 PM, MRAB wrote:

> Chris Hare wrote:
>> I am having a problem getting around this variable namespace thing.
>> Consider these code bits
>> File a.py
>> from Tkinter import *
>> import a1
>> def doAgain():
>> 	x = a1.Net()
>> 	x.show("Again!")
>> root = Tk()
>> root.title("test")
>> f = Frame(root,bg="Yellow")
>> l = Button(root,text="window 1",command=doAgain)
>> f.grid()
>> l.grid()
>> a = 5
>> x = a1.Net()
>> x.show("window 2")
>> if __name__ == "__main__":
>> 	root.mainloop()
>> File a1.py
>> from Tkinter import *
>> class Net:
>> 	def __init__(self):
>> 		self.window = Toplevel()
>> 	def show(self,t):		
>> 		self.l = Label(self.window,text=t)
>> 		self.l.grid()
>>                button = Button(self.window, text="Again")
>> 		button.bind("<Button-1>", self.Again)
>>                button2 = Button(self.window, text="Dismiss")
>> 		button2.bind("<Button-1>", self.hide)
>> 		button.grid()
>> 		button2.grid()
>> 	def Again(self,event):
>> 		x = Net()
>> 		x.show(a)
>> 	def hide(self,event):
>> 		self.window.destroy()
>> When I run a.py, it imports a1.py and click on the Again button, I get the error
>> Exception in Tkinter callback
>> Traceback (most recent call last):
>>  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/lib-tk/Tkinter.py", line 1410, in __call__
>>    return self.func(*args)
>>  File "/Volumes/Development/py/a1.py", line 17, in Again
>>    x.show(a)
>> NameError: global name 'a' is not defined
>> I believe this is the expected behavior.  so my question is this -- how do I tell the code in a1.py about the variable a, which exists in a.py?  Do I have to pass it as part of the function call, or what?  using
>> global a
>> in a1.py doesn't change anything.
>> since I am using SQLite for the disk database, I was thinking I could keep all the "global" variables in an in memory database and just access them when I need to, but other ideas are welcome.
> Why in a database? If you need the modules to share it then you could
> put it in a shared module and refer to it there:
> 
> File a.py
> ---------
> import my_globals
> ...
> my_globals.a = 5
> 
> 
> File a1.py
> ----------
> import my_globals
> ...
> 		x.show(my_globals.a)
> -- 
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