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Notes on Python variable scope

l Date: 2008-01-09  |   Modified: 2010-03-01  |   Tags: core, python   |   22 Comments

Example 1: The difference between global and local variables

Global variables are accessible inside and outside of functions. Local variables are only accessible inside the function. In the example below, the function can access both the global and the local variable. However, trying to access the local variable outside the function produces an error. 
global_var = 'foo'
def ex1():
    local_var = 'bar'
    print global_var
    print local_var

ex1()
print global_var
print local_var  # this gives an error

foo
bar
foo
Traceback (most recent call last):
  File "nested_scope.py", line 12, in 
    print local_var  # this gives an error
NameError: name 'local_var' is not defined

Example ...

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How to use *args and **kwargs in Python

l Date: 2008-01-03  |   Modified: 2010-03-15  |   Tags: core, python   |   85 Comments

Or, How to use variable length argument lists in Python.

The special syntax, *args and **kwargs in function definitions is used to pass a variable number of arguments to a function. The single asterisk form (*args) is used to pass a non-keyworded, variable-length argument list, and the double asterisk form is used to pass a keyworded, variable-length argument list. Here is an example of how to use the non-keyworded form. This example passes one formal (positional) argument, and two more variable length arguments. 

def test_var_args(farg, *args):
    print "formal arg:", farg
    for arg in args:
        print "another arg:", arg

test_var_args ...
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