# Scoping example for Python

# g is in the middle symbol table
g = 10

# f2 is in the middle symbol table
f2 = 15

# f1 is in the middle symbol table
f1 = 12
print 'initial:', g, f2, f1

# a new symbol table gets made when f1 is executed
def f1():
    # creates a new symbol g in the f1 symbol table
    # does not modify the middle symbol table entry
    g = 5

    # used to see if we can access this h from elsewhere
    h = 20

    global f2
    print 'g, f2 in f1():', g, f2

    # specifies that f2 should reference the middle symbol table

    # modifies f2 in the middle symbol table
    f2 = 25
    print 'f2 in f1():',f2

    # a new definition of f2, which actually modifies the middle symbol table
    def f2():
        global g
        g = 6

        print 'g,h in f2 post-assign:', g, h

    # a new definition of f3, which goes in the f1 symbol table
    def f3():
        # a new definition of f2 in the f3 symbol table
        f2 = 6
        print 'f2 in f3:', f2

    # still refers to the function
    print 'f2 in f1 post f2 def:', f2

    f2() # calls the function f2

    # refers to the g in f1
    print 'g in f1 post f2 call:', g

    f3() # calls the function f3

    # still refers to the function
    print 'f2 in f1 post f3 call:', f2


# prints the global g
print 'g, f2, f1 post f1 definition', g, f2, f1

# calls f1
f1()

# prints the global versions
print 'g, f2, f1 post f1 call', g, f2, f1

# f3 is not defined at the middle symbol table level
try:
    f3()
except:
    print 'unable to call f3()'

# see if f2 is defined as the function
f2()