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Local and global variables
Functions, Modules and Packages example from a Well House Consultants training course
More on Functions, Modules and Packages [link]

This example is described in the following article(s):
   • Sample code with errors in it on our web site - [link]

This example references the following resources:
http://www.wellho.net/course/ypfull.html

Source code: locvar.py Module: Y105
#!/usr/local/bin/python

# Variable scope

first = 1

def one():
        "Double a global variable, return it + 3."
        global first
        first *= 2
        result = first+3
        return result

print one.__doc__
print one()
print one()
print one()
print "first now has the value",first
print "result has the value",result

""" ----------------------------------------------------------

** Important Note **

This is an example from our training material and illustrates
variable scope in Python. The variable called result within the
one function is local to that function, so is not visible outside
and so the program generates an error when run, as follows:

earth-wind-and-fire:~/oct09 grahamellis$ python pyf
Double a global variable, return it + 3.
5
7
11
first now has the value 8
result has the value
Traceback (most recent call last):
  File "pyf", line 19, in ?
    print "result has the value",result
NameError: name 'result' is not defined
earth-wind-and-fire:~/oct09 grahamellis$

The subject of varaible scope and why "default local" is a good
idea is full covered in the training notes from which the code
above is copied ... see http://www.wellho.net/course/ypfull.html """

Learn about this subject
This module and example are covered on the following public courses:
 * Learning to program in Python
 * Python Programming
Also available on on site courses for larger groups

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Other Examples
This example comes from our "Functions, Modules and Packages" training module. You'll find a description of the topic and some other closely related examples on the "Functions, Modules and Packages" module index page.

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