__str__ method iterating over class attributes - python

I have a class with attributes made of several lists (today 8 but it'll grow for sure because my code relies on a previous code that is used on prod on another project)
This class has a __str__ function to pretty print information of the list. Today the function displays information about each list but calling them namely and I don't like that because every time my class attributes changes (add / remove list) I have to update this method
I'm looking for a way to dynamically iterate over my class attributes to display information
As an example, let's imagine the class below
class shopping_cart:
def __init__(self):
self.fruits = []
self.vegetables = []
self.meat = []
self.bread = []
def __str__(self):
msg = ""
msg += "shopping cart content\n"
msg += "---------------------\n"
msg += "---fruits-----------: " + len(self.fruits) +"\n
msg += "---vegetables-------: " + len(self.vegetables) +"\n
msg += "---meat-------------: " + len(self.meat) +"\n
msg += "---bread------------: " + len(self.bread) +"\n
return msg
As you can see the maintenance cost is high. I'm looking for something more dynamic, that will look more like
class shopping_cart:
def __init__(self):
self.fruits = []
self.vegetables = []
self.meat = []
self.bread = []
def __str__(self):
msg = ""
msg += "shopping cart content\n"
msg += "---------------------\n"
for item in <list of my class attributes>:
msg += "---" + item +"-----------: " + len(item) +"\n
return msg
Easy to read and easy to maintain.


I think the one functionality you are looking for is dir and getattr. Here is the example
class shopping_cart:
def __init__(self):
self.fruits = []
self.vegetables = []
self.meat = []
self.bread = []
def __str__(self):
msg = ""
msg += "shopping cart content\n"
msg += "---------------------\n"
members = [attr for attr in dir(self) if not callable(getattr(self, attr)) and not attr.startswith("__")]
for item in members:
msg += "---" + item +"-----------: " + str(getattr(self,item) )+"\n"
return msg


You could do that in a few ways:
1 - use the __dict__ attribute of your class. That gives you a dictionary object of all the variables, and you can iterate through them
s = shopping_cart()
s.__dict__
that should output something like
{'fruits':[], 'vegetables':[], ... }
2 - You could use a dictionary of lists, instead of a bunch of lists, and iterate on the dictionary.
3 - You could also use a list of lists (e.g. [self.fruits, self.vegetables...], and iterate on that.


You could use the built-in vars() function on an instance of the class (not the class itself):
class ShoppingCart:
def __init__(self):
self.fruits = []
self.vegetables = []
self.meat = []
self.bread = []
def __str__(self):
msg = "shopping cart contents\n"
msg += "----------------------\n"
for attrname in vars(self):
value = getattr(self, attrname)
if isinstance(value, list):
msg += "---{}{}: {:2}\n".format(
attrname, '-'*(15-len(attrname)), len(value))
return msg
cart = ShoppingCart()
print(cart)
Output:
shopping cart contents
----------------------
---fruits---------: 0
---vegetables-----: 0
---meat-----------: 0
---bread----------: 0

Related

I got some errors for implementation of GeneticAlgo

I am trying to make a time table scheduling program but found some errors. Please watch the following code and solve that error please.
Errors
These are the following errors
Traceback (most recent call last):
File "C:/Users/Muhammad Abbas/Downloads/ga02ClassScheduling.py", line 367, in <module>
population.get_schedules().sort(key=lambda x: x.get_fitness(), reverse=True)
File "C:/Users/Muhammad Abbas/Downloads/ga02ClassScheduling.py", line 367, in <lambda>
population.get_schedules().sort(key=lambda x: x.get_fitness(), reverse=True)
File "C:/Users/Muhammad Abbas/Downloads/ga02ClassScheduling.py", line 84, in get_fitness
self._fitness = self.calculate_fitness()
File "C:/Users/Muhammad Abbas/Downloads/ga02ClassScheduling.py", line 106, in calculate_fitness
if classes[i].get_room().get_seatingCapacity() < classes[i].get_course().get_maxNumbOfStudnets():
AttributeError: 'NoneType' object has no attribute 'get_seatingCapacity'
Source Code of the Program
Variables:
These are the variables which i declare for this program
import prettytable as prettytable
import random as rnd
POPULATION_SIZE = 9
NUMB_OF_ELITE_SCHEDULES = 1
TOURNAMENT_SELECTION_SIZE = 3
MUTATION_RATE = 0.1
Data Class
That is the first class which name is DATA
class Data:
ROOMS = [["R1", 25], ["R2", 45], ["R3", 35]]
MEETING_TIMES = [
["MT1", "MWF 09:00 - 10:00"],
["MT2", "MWF 10:00 - 11:00"],
["MT3", "TTH 09:00 - 10:30"],
["MT4", "TTH 10:30 - 12:00"]
]
INSTRUCTORS = [
["T1", "Dr James Web"],
["T2", "Mr Mike Brown"],
["T3", "Dr Steve Day"],
["T4", "Mrs Jane Doe"]
]
def __init__(self):
self._rooms = []
self._meetingTimes = []
self._instructors = []
for i in range(0, len(self.ROOMS)):
self._rooms.append(Room(self.ROOMS[i][0], self.ROOMS[i][1]))
for i in range(0, len(self.MEETING_TIMES)):
self._meetingTimes.append(MeetingTime(self.MEETING_TIMES[i][0], self.MEETING_TIMES[i][1]))
for i in range(0, len(self.INSTRUCTORS)):
self._instructors.append(Instructor(self.INSTRUCTORS[i][0], self.INSTRUCTORS[i][1]))
course1 = Course("C1", "325k", [self._instructors[0], self._instructors[1]], 25)
course2 = Course("C2", "319k", [self._instructors[0], self._instructors[1], self._instructors[2]], 35)
course3 = Course("C3", "462k", [self._instructors[0], self._instructors[1]], 25)
course4 = Course("C4", "464k", [self._instructors[2], self._instructors[3]], 30)
course5 = Course("C5", "360C", [self._instructors[3]], 35)
course6 = Course("C6", "303k", [self._instructors[0], self._instructors[2]], 45)
course7 = Course("C7", "303L", [self._instructors[1], self._instructors[3]], 45)
self._courses = [course1, course2, course3, course4, course5, course6, course7]
dept1 = Department("MATH", [course1, course3])
dept2 = Department("EE", [course2, course4, course5])
dept3 = Department("PHY", [course6, course7])
self._depts = [dept1, dept2, dept3]
self._numberOfClasses = 0
for i in range(0, len(self._depts)):
self._numberOfClasses += len(self._depts[i].get_courses())
def get_rooms(self):
return self._rooms
def get_instructors(self):
return self._instructors
def get_courses(self):
return self._courses
def get_depts(self):
return self._depts
def get_meetingTimes(self):
return self._meetingTimes
def get_numberOfClasses(self):
return self._numberOfClasses
Schedule Class
That is the second class which name is Schedule
class Schedule:
def __init__(self):
self._data = data
self._classes = []
self._numberOfConflicts = 0
self._fitness = -1
self._classNumb = 0
self._isFitnessChanged = True
def get_classes(self):
self._isFitnessChanged = True
return self._classes
def get_numberOfConflicts(self):
return self._numberOfConflicts
def get_fitness(self):
if(self._isFitnessChanged == True):
self._fitness = self.calculate_fitness()
self._isFitnessChanged = False
return self._fitness
def initialize(self):
depts = self._data.get_depts()
for i in range(0, len(depts)):
courses = depts[i].get_courses() #courses in each departments
for j in range(0, len(courses)):
newClass = Class(self._classNumb, depts[i], courses[j])
self._classNumb += 1
newClass.set_meetingTime(data.get_meetingTimes()[rnd.randrange(0, len(data.get_meetingTimes()))])
newClass.set_room(data.get_rooms()[rnd.randrange(0, len(data.get_rooms()))])
newClass.set_instructor(courses[j].get_instructors()[rnd.randrange(0, len(courses[j].get_instructors()))])
self._classes.append(newClass)
return self
def calculate_fitness(self):
self._numberOfConflicts = 0
classes = self.get_classes()
for i in range(0, len(classes)):
if classes[i].get_room().get_seatingCapacity() < classes[i].get_course().get_maxNumbOfStudnets():
self._numberOfConflicts += 1
for j in range(0, len(classes)):
if(j >= i):
if(classes[i].get_meetingTime() == classes[j].get_meetingTime() and
classes[i].get_id() != classes[j].get_id()):
if(classes[i].get_room() == classes[j].get_room()):
self._numberOfConflicts += 1
if(classes[i].get_instructor() == classes[j].get_instructor()):
self._numberOfConflicts += 1
return 1 / ((1.0*self._numberOfConflicts + 1))
def __str__(self):
# it returns all the classes of schedule separated by comas
returnValue = ""
for i in range(0, len(self._classes)):
returnValue += str(self._classes[i]) + ", "
returnValue += str(self._classes[len(self._classes)-1])
return returnValue
Population Class
Thats the third class which is Population class
class Population:
def __init__(self, size):
self._size = size
self._data = data
self._schedules = []
for i in range(0, size):
self._schedules.append(Schedule().initialize())
def get_schedules(self):
return self._schedules
GeneticAlgorithm Class
Thats the fourth class which is the GeneticAlgorithm class
class GeneticAlgorithm:
def evolve(self, population):
return self._mutate_population(self._crossover_population(population))
def _crossover_population(self, pop):
crossover_pop = Population(0)
for i in range(NUMB_OF_ELITE_SCHEDULES):
crossover_pop.get_schedules().append(pop.get_schedules()[i])
i = NUMB_OF_ELITE_SCHEDULES
while i < POPULATION_SIZE:
schedule1 = self._select_tournament_population(pop).get_schedules()[0]
schedule2 = self._select_tournament_population(pop).get_schedules()[0]
crossover_pop.get_schedules().append(self._crossover_schedule(schedule1, schedule2))
i += 1
return crossover_pop
def _mutate_population(self, population):
for i in range(NUMB_OF_ELITE_SCHEDULES, POPULATION_SIZE):
self._mutate_schedule(population.get_schedules()[i])
return population
def _crossover_schedule(self, schedule1, schedule2):
crossoverSchedule = Schedule().initialize()
for i in range(0, len(crossoverSchedule.get_classes())):
if (rnd.random() > 0.5):
crossoverSchedule.get_classes()[i] = schedule1.get_classes()[i]
else:
crossoverSchedule.get_classes()[i] = schedule2.get_classes()[i]
return crossoverSchedule
def _mutate_schedule(self,mutateSchedule):
schedule = Schedule().initialize()
for i in range(0, len(mutateSchedule.get_classes())):
if(MUTATION_RATE > rnd.random()):
mutateSchedule.get_classes()[i] = schedule.get_classes()[i]
return mutateSchedule
def _select_tournament_population(self, pop):
tournament_pop = Population(0)
i = 0
while i < TOURNAMENT_SELECTION_SIZE:
tournament_pop.get_schedules().append(pop.get_schedules()[rnd.randrange(0, POPULATION_SIZE)])
i += 1
tournament_pop.get_schedules().sort(key=lambda x:x.get_fitness(), reverse=True)
return tournament_pop
Course Class
Thats the fifth class which is the Course class
class Course:
def __init__(self, number, name, instructors, maxNumbOfStudents):
self._number = number
self._name = name
self._instructors = instructors
self._maxNumbOfStudents = maxNumbOfStudents
def get_name(self):
return self._name
def get_number(self):
return self._number
def get_instructors(self):
return self._instructors
def get_maxNumbOfStudents(self):
return self._maxNumbOfStudents
def __str__(self):
return self._name
Instructor Class
Thats the sixth class which is Instructor class
class Instructor:
def __init__(self, id, name):
self._id = id
self._name = name
def get_id(self):
return self._id
def get_name(self):
return self._name
def __str__(self):
return self._name
Room Class
Thats the seventh class which is the Room Class
class Room:
def __init__(self, number, seatingCapacity):
self._number = number
self._seatingCapacity = seatingCapacity
def get_number(self):
return self._number
def get_seatingCapacity(self):
return self._seatingCapacity
MeetingTime Class
Thats the eighth class which is MeetingTime class
class MeetingTime:
def __init__(self, id, time):
self._time = time
self._id = id
def get_id(self):
return self._id
def get_time(self):
return self._time
Department Class
Thats the ninth class which is the Department class
class Department:
# Batch for my case
def __init__(self, name, courses):
self._name = name
self._courses = courses # Courses that department offers
def get_name(self): return self._name
def get_courses(self): return self._courses
Class class
Thats is the tenth class which name is Class
class Class:
# Course to be scheduled at specific room of department host by an instructor at specific Meeting Time
def __init__(self, id, dept, course):
self._id = id
self._dept = dept
self._course = course
self._instructor = None
self._meetingTime = None
self._room = None
def get_id(self):
return self._id
def get_dept(self):
return self._dept
def get_room(self):
return self._room
def get_course(self):
return self._course
def get_instructor(self):
return self._instructor
def get_meetingTime(self):
return self._meetingTime
def set_instructor(self, instructor):
self._instructor = instructor
def set_meetingTime(self, meetingTime):
self._meetingTime = meetingTime
def set_room(self, room):
self_room = room
def __str__(self):
return str(self._dept.get_name()) + "," + str(self._course.get_number()) + "," + \
str(self._room.get_number()) + "," + str(self._instructor.get_id()) + "," + str(self._meetingTime.get_id())
DisplayMgr Class Plus End Code
Thats the eleventh class which is DisplayMgr Class and the end code of that program.
class DisplayMgr:
def print_available_data(self):
print("> All Available Data")
self.print_dept()
self.print_course()
self.print_room()
self.print_instructor()
self.print_meeting_times()
def print_dept(self):
depts = data.get_depts()
availableDeptsTable = prettytable.PrettyTable(['dept', 'courses'])
for i in range(0, len(depts)):
courses = depts.__getitem__(i).get_courses()
tempStr = "["
for j in range(0, len(courses) - 1):
tempStr += courses[j].__str__() + ", "
tempStr += courses[len(courses) - 1].__str__() + "]"
availableDeptsTable.add_row([depts.__getitem__(i).get_name(), tempStr])
print(availableDeptsTable)
def print_course(self):
availabelCoursesTable = prettytable.PrettyTable(['id', 'course # ', 'max # of students', 'instructors'])
courses = data.get_courses()
for i in range(0, len(courses)):
instructors = courses[i].get_instructors()
tempStr = ""
for j in range(0, len(instructors)-1):
tempStr += instructors[j].__str__() + ", "
tempStr += instructors[len(instructors) - 1].__str__()
availabelCoursesTable.add_row(
[courses[i].get_number(), courses[i].get_name(), str(courses[i].get_maxNumbOfStudents()), tempStr]
)
print(availabelCoursesTable)
def print_instructor(self):
availableInstructorsTable = prettytable.PrettyTable(['id', 'instructor'])
instructors = data.get_instructors()
for i in range(0, len(instructors)):
availableInstructorsTable.add_row([instructors[i].get_id(), instructors[i].get_name()])
print(availableInstructorsTable)
def print_room(self):
availableRoomsTable = prettytable.PrettyTable(['room #', 'max seating capacity'])
rooms = data.get_rooms()
for i in range(0, len(rooms)):
availableRoomsTable.add_row([str(rooms[i].get_number()), str(rooms[i].get_seatingCapacity())])
print(availableRoomsTable)
def print_meeting_times(self):
availableMeetingTimeTable = prettytable.PrettyTable(['id', 'Meeting Time'])
meetingTimes = data.get_meetingTimes()
for i in range(0, len(meetingTimes)):
availableMeetingTimeTable.add_row([meetingTimes[i].get_id(), meetingTimes[i].get_time()])
print(availableMeetingTimeTable)
def print_generation(self, population):
table1 = prettytable.PrettyTable(['schedule # ', 'fitness', '# of Conflicts','classes [dept, class, room, instructor'])
schedules = population.get_schedules()
for i in range(0, len(schedules)):
table1.add_row([str(i), round(schedules[i].get_fitness(),3), schedules[i].get_numberOfConflicts(), schedules[i]])
print(table1)
def print_schedule_as_table(self, schedule):
classes = schedule.get_classes()
table = prettytable.PrettyTable(['Class # ', 'Dept', 'Course (number, max # of students)', 'Room (Capacity', 'Instructor'])
for i in range(0, len(classes)):
table.add_row([str(i), classes[i].get_dept().get_name(), classes[i].get_course().get_name() + " (" +
classes[i].get_course().get_number() + ", " +
str(classes[i].get_course().get_maxNumbOfStudents()) + ")",
classes[i].get_room().get_number() + " (" + str(classes[i].get_room().get_seatingCapacity()) +
classes[i].get_instructor().get_name() + " (" + str(classes[i].get_instructor().get_id()) +")",
classes[i].get_meatingTime().get_time() + " (" + str(classes[i].get_meatingTime().get_id()) +")"
])
print(table)
data = Data()
displayMgr = DisplayMgr()
displayMgr.print_available_data()
generationNumber = 0
print("\n> Generation # " + str(generationNumber))
population = Population(POPULATION_SIZE)
population.get_schedules().sort(key=lambda x: x.get_fitness(), reverse=True)
displayMgr.print_generation(population)
displayMgr.print_schedule_as_table(population.get_schedules()[0]) # it will print fittest generation of schedule
geneticAlgorithm = GeneticAlgorithm()
while (population.get_schedules()[0].get_fitness() != 1.0):
generationNumber += 1
print("\n> Generation # " + str(generationNumber))
population = geneticAlgorithm.evolve(population)
population.get_schedules().sort(key=lambda x: x.get_fitness(), reverse=True)
displayMgr.print_generation(population)
displayMgr.print_schedule_as_table(population.get_schedules()[0])
print("\n\n")

def set_room(self, room):
self_room = room
you have missing . in set_room(self,room) function . Change it to self._room=room so that it will set the room value and objectType=None will be solved

Look into your the class DisplayMgr/def print_schedule_as_table
Change classes[i].get_meatingTime().get_time() to meetingTime

How to assign return value to __init__ value

I am trying to assign the return values of getItem and getBuyingType to the self variables in the __init__ method in my Ebay Scraper function. How can I do this? If it's not possible, is there another way to assign the outputs of these two functions to be part of the Ebay Scraper class? Item should be assigned to self.item and buying_type to self.buying_type.
class EbayScraper(object):
def __init__(self):
self.base_url = "https://www.ebay.com/sch/i.html?_nkw="
self.item =
self.buying_type =
self.url_seperator = "&_sop=12&rt=nc&LH_"
self.url_seperator2 = "&_pgn="
self.page_num = "1"
self.currentPage = 1
def getItem(self):
item = input("Item: ")
return item
def getBuyingType(self):
buying_type = input("Please specify a buying type (Auction or Buy It Now): ")
buying_type = buying_type.lower()
if buying_type == "auction":
return buying_type + "=1"
elif buying_type == "buy it now":
return buying_type + "=1"
else:
print("Invalid buying type specified.")
self.getBuyingType()

You can call functions inside __init__ method
def __init__(self):
...
self.item = self.getItem()

The proper way to do this is to simply pass arguments to __init__ to initialize the values. If you want to provide an interactive method for providing those arguments, define a class method.
class EbayScraper(object):
def __init__(self, item, buying_type):
self.base_url = "https://www.ebay.com/sch/i.html?_nkw="
self.item = item
self.buying_type = buying_type
self.url_seperator = "&_sop=12&rt=nc&LH_"
self.url_seperator2 = "&_pgn="
self.page_num = "1"
self.currentPage = 1
#classmethod
def prompt_user(cls):
item = input("Item")
while True:
buying_type = input("Please specify a buying type...").lower()
if buying_type in ('auction', 'buy it now'):
break
print("Invalid buying type specified")
return cls(item, buying_type + "=1")
e = EbayScraper.prompt_user()

how to call function dynamically

I have a class containing several lists as attributes and several add methods to append an object to a specific list based on its type.
My code reads a csv file containing the type of an object in order to create and add it to my cart.
My problem is that I'm testing the object type to call the right 'add' function using if elif syntax but this is not very nice and hard to maintain.
For example
import csv
class my_item():
def __init__(self, name):
self.name = name
class fruit(my_item):
pass
class vegetable(my_item):
pass
class meat(my_item):
pass
class fish(my_item):
pass
class shopping_cart():
def __init__(self):
self.fruits = []
self.vegetables = []
self.meat = []
self.fish = []
def add_fruit(self, o):
self.fruits.append(o)
def add_vegetable(self, o):
self.vegetables.append(o)
def add_meat(self, o):
self.meat.append(o)
def add_fish(self, o):
self.fish.append(o)
def __str__(self):
msg = ""
msg += "{:<25}= {:<5}\n".format('Total', str(len(self.fruits) + len(self.vegetables) + len(self.meat) + len(self.fish)))
for attrname in vars(self):
value = getattr(self, attrname)
if isinstance(value, list):
msg += " {:<23}= {:<5}\n".format(attrname, len(value))
return msg
def main():
input_f = 'input.csv'
my_cart = shopping_cart()
with open(input_f, 'r') as i:
rows = csv.reader(i, delimiter=';')
for row in rows:
item = globals()[row[0]](row[1])
if item.__class__.__name__ == 'fruit':
my_cart.add_fruit(item)
elif item.__class__.__name__ == 'vegetable':
my_cart.add_vegetable(item)
elif item.__class__.__name__ == 'meat':
my_cart.add_meat(item)
else:
my_cart.add_fish(item)
print (my_cart)
if __name__ == '__main__':
main()
Do you see any alternatives to the if elif block?
Thanks for your feedback.

Sure, you just need to create the function name dynamically and call it.
Be careful, this will works only if my_cart have add_{{ item name }} method.
def main():
input_f = 'input.csv'
my_cart = shopping_cart()
with open(input_f, 'r') as i:
rows = csv.reader(i, delimiter=';')
for row in rows:
item = globals()[row[0]](row[1])
item_name = item.__class__.__name__
item_add_func_name = 'add_{}'.format(item_name)
item_add_func = getattr(my_cart, item_add_func_name, None)
if item_add_func and callable(item_add_func):
item_add_func(item)
# if item.__class__.__name__ == 'fruit':
# my_cart.add_fruit(item)
# elif item.__class__.__name__ == 'vegetable':
# my_cart.add_vegetable(item)
# elif item.__class__.__name__ == 'meat':
# my_cart.add_meat(item)
# else:
# my_cart.add_fish(item)
print (my_cart)

May I suggest a simpler class design.
my_item is left as it-is and other classes fruit, vegetable etc. are removed
shopping_cart is modified such that self.items is a dictionary where the key is the name of item, fruit, vegetables, and the values are the list of those items
Then the code might look like as follows
import csv
from collections import defaultdict
class my_item:
def __init__(self, name):
self.name = name
class shopping_cart:
def __init__(self):
#Dictionary to hold items
self.items = defaultdict(list)
def add_item(self, type, name):
#Increment the count of the item by 1
self.items[type].append(name)
def __str__(self):
#Iterate through the dictionary and print all key/value pairs
msg = ""
for k,v in self.items.items():
msg += ' {}: {} '.format(k, v)
return msg.strip()
sc = shopping_cart()
sc.add_item('fruit', 'pomme')
sc.add_item('vegetable', 'dinde')
sc.add_item('meat', 'carotte')
sc.add_item('fish', 'saumon')
print(sc)
The output will look like
fruit: ['pomme'] vegetable: ['dinde'] meat: ['carotte'] fish: ['saumon']

TypeError: unbound method getInterfaceName() must be called with Interface instance as first argument (got nothing instead)

class Unit:
def init(self, _chassisId, _unitNo, _interface):
self.chassisId = _chassisId
self.unitNo = _unitNo
self.interface = _interface
def getInterface(self):
return self.interface
#staticmethod
def parse(elem):
unitList = elem.find(UNIT+LIST)
chassisList = []
for unit in unitList.findall(UNIT):
try:
unitNumber = unit.find(UNIT_NUMBER).text
interface = unit.find(INTERFACE)
interface = ""
chassisIdElem = unit.find(CHASSIS_ID)
chassisId = ""
if chassisIdElem is not None:
chassisId = unit.find(CHASSIS_ID).text
elif unit.find(BURNED_IN_MAC) is not None:
chassisId = unit.find(BURNED_IN_MAC).text
chassisId = chassisId.replace(".", "").replace(":", "").upper()
chassis = Unit(chassisId, interface, unitNumber)
chassisList.append(chassis)
except Exception as e:
print "Unit details not found", e
return chassisList
def getChassisId(self):
return self.chassisId
def __str__(self):
str = "\n"
str += "\nUnit Details:- "
len = str.__len__();
str += "\n"
for i in range(1,len-1):
str += "-"
str += "\nUnit: " + self.unitNo
str += "\nChassis Id: " + self.chassisId
str += "\nInterfaces: " + self.interfaces
return str
def __add__(self, other):
return str(self) + other
def __radd__(self, other):
return other + str(self)
class Interface:
def init(self, _linkState, _interfaceName):
self.linkState = _linkState
self.interfaceName = _interfaceName
#staticmethod
def parse(elem):
prefix = Device.getPrefix(elem.tag)
interfaceList = elem.find(INTERFACE + LIST)
interfaceNameTag = eval(prefix + "_INTERFACE_NAME")
linkStateTag = eval(prefix + "_LINK_STATE")
interfaces = []
for interface in interfaceList.findall(INTERFACE):
try:
interfaceName = interface.find(interfaceNameTag).text
linkStateElem = interface.find(LINK_STATE)
linkState = ""
if linkStateElem is not None:
linkState = interface.find(LINK_STATE).text
elif interface.find(LINE_PROTOCOL) is not None:
linkState = interface.find(LINE_PROTOCOL).text
interface = Interface(linkState, Name)
interfaces.append(interface)
except Exception as e:
print "Interface details not found", e
return interfaces
def getLinkState(self):
return self.linkState
def getInterfaceName(self):
return self.interfaceName
def __str__(self):
str = "\n"
str += "\nInterface Details:- "
len = str.__len__();
str += "\n"
for i in range(1,len-1):
str += "-"
str += "\nLink State: " + self.linkState
str += "\nInterface Name: " + self.interfaceName
return str
def __add__(self, other):
return str(self) + other
def __radd__(self, other):
return other + str(self)

You haven't shown us the call to getInterfaceName() that causes the error, which makes it harder to help you.
However, I'll guess that the call looks something like this:
something = Interface.getInterfaceName()
You can't do it that way. You must create an instance of Interface, and then call its .getInterfaceName() method:
myInterface = Interface()
something = myInterface.getInterfaceName()

Shopping Cart and item class in python, issue with accessing objects from one class and using them in another

Attempting to create a program in python 3 that takes object(s) created from one class item to another, shoppingCart. The idea is to create a list of objects created by the item class using the shoppingCartclass, while still being able to access attributes of the item class such as price and quantity.
class item:
def __init__(self,n,p,q):
self.name = n
self.price = p
self.quantity = q
def show(self):
z = (str(self.name))
print(z)
self1 =("$")+(str(self.price))
print(self1)
def getName(self):
return self.name
def getPrice(self):
return ("$") + str(self.price)
def getQuantity(self):
return self.quantity
class shoppingCart:
def __init__(self, items):
self.items = []
def show(self):
print(self.items)
def addItem(self,item):
if item not in self.items:
self.items.append(item)
else:
item.q += 1
def deleteItem(self,item):
if item in self.items:
self.items.remove(item)
else:
return print("Not in Cart")
def checkOut (self):
total = 0
for i in self.items:
price = i[1]
total += price
return total
item1 = item("Chocolate",5 ,3)
item2 = item("Bacon",15,1)
item3 = item("Eggs",2,5)
c = shoppingCart([])
c.addItem(item1)
c.addItem(item2)
c.addItem(item3)
c.show()
print ("You have 3 items in your cart for a total of" (c.checkOut()))
c.removeItem(item3)
print ("You have 2 items in your cart for a total of" (c.checkOut()))
The above code currently creates two errors, firstly, the c.show is printing the IDs of the objects appended to the shopping cart. In addition, the checkOut method creates an error regarding price = i[1] saying that the item object does not support indexing. Alternate solutions to this problem that still bares some resemblance to my original code will be welcome!

First, c.show() prints the list, but you haven't defined __str__ or __repr__ for your classes, so you're stuck with the default representation. Try e.g.
def __str__(self):
return str(self.name)
Then you can:
print(map(str, self.items))
Alternatively, use your item.show:
for i in self.items:
i.show()
Second, in checkOut, i is an item, which you can't index into. If you want its price, use dot notation: i.price.

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