UnboundLocalError: local variable referenced before assignment

[Bryan]

ch1zra wrote:
> I have following code :
>
> import os, time, re, pyodbc, Image, sys
> from datetime import datetime, date, time
> from reportlab.lib.pagesizes import A4
> from reportlab.lib.units import cm
> from reportlab.pdfgen import canvas
> from reportlab.pdfbase import pdfmetrics
> from reportlab.pdfbase.ttfonts import TTFont
> import mkTable
>
> mkTable.mkTable()
>
> and then file mkTable.py located in same directory has :
>
> def mkTable():
>     global canvas
>     canvas = canvas.Canvas(fname, pagesize=A4)
>     ... and so on
>
> this gives me following traceback:
>
> Traceback (most recent call last):
>   File "C:\py\pdf_test.py", line 36, in <module>
>     mkTable.mkTable()
>   File "C:\py\mkTable.py", line 38, in mkTable
>     canvas = canvas.Canvas("K_lista.pdf", pagesize=A4)
> UnboundLocalError: local variable 'canvas' referenced before
> assignment

Python doesn't have one global namespace. Each module (file) has its
own namespace, which is a Python dict, and 'global' means defined in
the containing module's dict. Put the import:

  from reportlab.pdfgen import canvas

in the mkTable.py file. That brings 'canvas' into the mkTable module's
namespace.

Python programs commonly import the same module multiple times. Only
the first import runs the body of the imported module. Subsequent
imports merely bring the names into the importing module's namespace.


--
--Bryan Olson