classReg | Python Fiddle

__author__ = 'jsgreenwell'

from random import randrange

class RegisterFunctions:
    """
    Basic Class example, includes additional methods and attributes that are not used now but will be expanded.
    Current initialization is with or without sales_rep (sets a default value when not passed).
    """

def __init__(self, sales_rep=12515):
        """
        Sets basic variables and initiates class.
        payment is set so it can be accessed directly from main for calculations
        purchases may be needed later (Tk will display a screen of just purchases)
        total is also used for calculates
        :param sales_rep: defaults to 12515; not used at the moment
        """
        self.transactionNum = randrange(1222, 4000) #TODO: Unique identifier
        self.purchases = {}
        self.rep = sales_rep
        self.payment = 0.0
        self.total = 0.0

def gettransaction(self):
        """
        :return: transactionNum
        """
        return self.transactionNum

def addpurchase(self, item_id, item_name, item_qty, item_price):
        """
        Adds a purchased item to the purchases attribute
        :param item_id: id of item being purchased
        :param item_name: name of the item
        :param item_qty: number of items being purchased
        :param item_price: price of the item being purchased
        """
        #This will probably be added as (self, item_id, list) with *
        self.purchases[item_id] = {"name": item_name, "qty": item_qty, "price": item_price}

def getpurchases(self):
        """ :return: stringified version of the purchases dict for error testing mostly """
        return str(self.purchases)

def changeqty(self, item_id, change, amount):
        """
        Increase or decrease the amount of items purchased
        :param item_id: id of item to change
        :param change: type of change - increase qty or decrease
        :param amount: number to change
        :return:
        """
        if change == "inc":
            self.purchases[item_id]["qty"] += amount
        elif change == "decr":
            self.purchases[item_id]["qty"] -= amount

def voiditem(self, item_id):
        """ Removes passed item from purchases list """
        self.purchases.pop(item_id, None)

def voidpurchase(self):
        """ Empties purchases (voids transaction) """
        self.purchases.clear()

def pricecorrection(self, item_id, correct_type, new_price):
        """
        Manually corrects a price for special promotions, errors, and other reasons
        :param item_id: id of item
        :param correct_type: price = set price to given price, discount = subtract from price, percent = take off percentage
        :param new_price: amount to decrease price
        """
        #add a log print here with some passed given reason and self.rep
        if correct_type == "price":
            self.purchases[item_id]["price"] = new_price
        elif correct_type == "discount":
            self.purchases[item_id]["price"] -= new_price
        elif correct_type == "percent":
            self.purchases[item_id]["price"] -= self.purchases[item_id]["price"] * new_price

def changerep(self, new_rep):
        #also log print
        self.rep = new_rep

def calctotalsale(self):
        """
        Calculates the total price due.
        :return: totalsale: the Sale Price Total
        """
        totalsale = 0.0

for items in self.purchases.keys():
            totalsale += self.purchases[items]["price"] * self.purchases[items]["qty"]
        self.total = totalsale
        return totalsale

def addpayment(self, pay_amount):
        """ Adds passed pay_amount to the total payment attribute """
        self.payment += pay_amount

def getchange(self):
        """
        Reduce diff_owed until less than each denomination and add to a count of each denomination showing how much of
        each bill and coinage to give as change. This is the actual knapsack problem.
        :return: String displaying the change due or if an Error has occurred
        """
        change = 0.0
        denominations = (20.0, 10.0, 5.0, 1.0, .25, .1, .05, .01)

if self.payment == self.total:
            return 'Change due: $0.00'
        elif self.payment > self.total:
            diff_owed = self.payment - self.total
            return_string = "Change due is ${0:.2f}. Need:\n".format(diff_owed)
            for den in denominations:
                den_count = 0
                while diff_owed >= den:
                    den_count += 1
                    diff_owed -= den
                return_string += "  {0:.2f}: {1}\n".format(den, den_count)
            return return_string
        return "Error processing payment"

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