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|---|---|
| From | John Gordon <gordon@panix.com> |
| Newsgroups | comp.lang.python |
| Subject | Re: What's wrong with this code? (UnboundLocalError: local variable referenced before assignment) |
| Date | Mon, 24 Jun 2013 20:12:49 +0000 (UTC) |
| Organization | PANIX Public Access Internet and UNIX, NYC |
| Lines | 38 |
| Message-ID | <kqa981$9uu$1@reader2.panix.com> (permalink) |
| References | <b3d3518a-f24a-4c32-a41a-b99145753528@googlegroups.com> |
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| Xref | csiph.com comp.lang.python:49074 |
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In <b3d3518a-f24a-4c32-a41a-b99145753528@googlegroups.com> pablobarhamalzas@gmail.com writes:
> isWhite = True
>
> def change(event):
> if event.x > x1 and event.x < x2 and event.y > y1 and event.y < y2:
> if isWhite:
> w.itemconfig(rect, fill="blue")
> isWhite = False
> else:
> w.itemconfig(rect, fill="white")
> isWhite = True
>
> w.bind("<Button-1>", change)
>
> root.mainloop()
> The problem occurs when clicking on the white square. The following error
> appears:
> "if isWhite:
> UnboundLocalError: local variable 'isWhite' referenced before assignment"
> However, the isWhite variable is clearly defined at "True" a few lines
> before.
Since you're new to programming, this might be a bit tricky to explain,
but I'll do my best. :-)
The problem is that change() isn't being executed here; instead it's being
executed from within root.mainloop(), whenever the user presses button-1.
And within root.mainloop(), there is no variable called isWhite.
--
John Gordon A is for Amy, who fell down the stairs
gordon@panix.com B is for Basil, assaulted by bears
-- Edward Gorey, "The Gashlycrumb Tinies"
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What's wrong with this code? (UnboundLocalError: local variable referenced before assignment) pablobarhamalzas@gmail.com - 2013-06-24 12:47 -0700
Re: What's wrong with this code? (UnboundLocalError: local variable referenced before assignment) pablobarhamalzas@gmail.com - 2013-06-24 12:53 -0700
Re: What's wrong with this code? (UnboundLocalError: local variable referenced before assignment) Peter Otten <__peter__@web.de> - 2013-06-24 22:05 +0200
Re: What's wrong with this code? (UnboundLocalError: local variable referenced before assignment) Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-24 22:10 +0200
Re: What's wrong with this code? (UnboundLocalError: local variable referenced before assignment) John Gordon <gordon@panix.com> - 2013-06-24 20:12 +0000
Re: What's wrong with this code? (UnboundLocalError: local variable referenced before assignment) Joshua Landau <joshua.landau.ws@gmail.com> - 2013-06-24 21:33 +0100
Re: What's wrong with this code? (UnboundLocalError: local variable referenced before assignment) Dave Angel <davea@davea.name> - 2013-06-24 16:43 -0400
Re: What's wrong with this code? (UnboundLocalError: local variable referenced before assignment) John Gordon <gordon@panix.com> - 2013-06-24 21:41 +0000
Re: What's wrong with this code? (UnboundLocalError: local variable referenced before assignment) pablobarhamalzas@gmail.com - 2013-06-24 13:19 -0700
Re: What's wrong with this code? (UnboundLocalError: local variable referenced before assignment) Joshua Landau <joshua.landau.ws@gmail.com> - 2013-06-24 21:33 +0100
Re: What's wrong with this code? (UnboundLocalError: local variable referenced before assignment) Joshua Landau <joshua.landau.ws@gmail.com> - 2013-06-24 21:19 +0100
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