# File: scope.py
# Program to demonstrate how functions handle variables
# This version focuses on variable scope *only*
#
# Matt Bishop, COSMOS 2012, Cluster 4
#

#
# let's define something for main
#
k = 1

#
# this function has k as a local variable
# changes do not affect the value of k in main
#
def func1():
    k = 2
    print("In func1, k's value is", k)

#
# this function refers to the k defined at the top
# of the file (that is, main's k)
# the "global k" makes this happen
# changes here do affect the value of k in main
#
def func2():
    global k
    k = 3
    print("In func2, k's value is", k)

#
# this function refers to the k in the parameter list
# so, in effect, k is a local variable
# changes do not affect the value of k in main
# (note: 
#
def func3(k):
    print("As an argument to func3, the parameter k's value is", k)
    k = 4
    print("In func3, k's value is", k)
    
#
# now for the main routine
# the k here refers to the one at the top of the file
#
print("Initially, k's value is", k)
#
# func1() will not change k's value
#
func1()
print("After func1, k's value is", k)
#
# func2() *will* change k's value
#
func2()
print("After func2, k's value is", k)
#
# for clarity, now reset it to the initial value
#
k = 1
print("After reassignment, k's value is", k)
#
# func3() will not change k's value
#
func3(k)
print("After func3, k's value is", k)