# Skeleton version of an object-oriented approach to segmental phonology to illustrate OO concepts

# Phone object class
# A phone here is not any particular type of class, just a general object
class phone(object):

    # Used when creating a new phone object
    # Assign the symbol to represent the phone
    def __init__(self, symbol='a'):
        self.symbol = symbol

    # How to print a symbol object
    def __str__(self):
        return self.symbol

    # Retrieve the symbol from the object
    def getSymbol(self):
        return self.symbol

    # Compare two phones on the basis of the ASCII value of their representations
    # This is merely for illustrative purposes
    def __cmp__(self, other):
        if self.symbol < other.symbol:
            return -1
        elif self.symbol > other.symbol:
            return 1
        else:
            return 0

# A consonant is a type of phone and thus inherits from it
# It thus has all behavior of phones (plus anything new)
class consonant(phone):

    # Change the voicing on a consonant if it's in /ptkbdg/
    # Only consonants will be able to do this as defined
    def changeVoicing(self):
        if self.symbol == 't':
            self.symbol = 'd'
        elif self.symbol == 'd':
            self.symbol = 't'
        elif self.symbol == 'p':
            self.symbol = 'b'
        elif self.symbol == 'b':
            self.symbol = 'p'
        elif self.symbol == 'k':
            self.symbol = 'g'
        elif self.symbol == 'g':
            self.symbol = 'k'

# Another inheritor of phone    
class vowel(phone):

    # We don't define any useful additional functionality, so just use a placeholder
    pass