Variable Scope Demo (Python)

'''
In Python variables declared outside of any function/procedure/loop etc are
available to the whole script.
They are READ ONLY inside a function/procedure by default
Downside:
You have to add the global keyword inside EVERY function that wants to modify them
Upside:
It encourages you to pass variables between functions/procedures, rather than using global ones

Variables declared inside functions/procedures/loops are local to that code block
They are deleted when the code block is ended (Similar to C#)
'''
globalDemoVariable = "Hello World" #global to the whole of this script (in theory)

def pythonScopeDemo():
    #global globalDemoVariable # un-comment this line (and line 18) to allow line 18 to work
    print(globalDemoVariable)
    #globalDemoVariable = "Goodbye" # un-comment this line (and line 16) to allow this to work
    print(globalDemoVariable)

    localDemoVariable = "this is a local string variable"
    print(localDemoVariable)

def main():
    pythonScopeDemo()
    # the next line will cause an error because localDemoVariable does not exist any more
    #print(localDemoVariable) # un-comment this line to see the error of your ways...

main()