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.
The global keyword does not make a variable global. It tells the
interpreter that the variable in question can be find in the module
scope, not the function/method scope. In other words, the variable is
global to the module, but not to the whole program.
What you'll need to do is pass a into Net when you instanciate it, like
so (untested):
def doAgain():
x = a1.Net(a)
x.show("Again!")
and in Net:
class Net:
def __init__(self, some_number):
self.some_number = some_number
self.window = Toplevel()
.
.
.
def Again(self,event):
x = Net(self.some_number)
x.show()
Keep in mind, though, that if you change a in a.py after you've
instanciated Net, your Net instance will not see the change. For the
change to show up, a would need to be mutable, and you would have to
mutate it. The other option is to change the Net instance's some_number
directly (i.e. x.some_number = 9).
Hope this helps.
~Ethan~
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