Python Function Scope - Global vs Local

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Variable Scope

Scope refers to the parts of a program or function in which a variable is relevant.

Global Variables

These variables are set at the program level and are available at any point after they are initiated.

If a variable is called inside a function but cannot be found initiated within that function, Python will look for its value in the Global scope.

You can create a global variable from within a function with the global keyword.

E.g.

artist = "Michael Jackson"

def printer(artist):
    global internal_var 
    internal_var = "Whitney Houston"
    print(artist, "is an artist")

printer(artist) 
printer(internal_var)

>>> Michael Jackson is an artist
>>> Whitney Houston is an artist

Local Variables

These variables are available only within the function in which they were initialised, and can only be made visible to the program at large as a return value.

If we try do the previous example without the global keyword, this nature is made apparent with the following error.

artist = "Michael Jackson"

def printer(artist):
    internal_var= "Whitney Houston"
    print(artist,"is an artist")

printer(artist) 
printer(internal_var)

Michael Jackson is an artist

> 10 printer1(internal_var1)

NameError: name 'internal_var1' is not defined