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Lec 18 Classes

Assignment Updates

Stuff due soon:

  • HW6 Due Wednesday (Files)
  • Participation due Thursday
  • Quiz due Thursday
  • Lab on Friday
  • Capstone Proposal Due Friday



Counter Code:

class Counter:
def __init__(self, start):
self.count = start
def inc(self):
self.count += 1

my_counter = Counter(5)

Undo Code:

# This class is a blueprint for an object that can be used to store a value that can be changed and undone
class Undo:

# This is the constructor (it is called when the object is created)
def __init__(self, start_value=0):
# History is a list of values that have been set previously
self.history = [start_value]
# History index stores the index of the current value that is being used
self.history_index = 0

# This method sets the value of the object (in a way that can be undone)
def set(self, new_value):
# If we have undone some changes, and we want to make a new change, we need to delete the changes that we have undone
# To do this, we remove everything after the current index (using slicing)
self.history = self.history[:self.history_index + 1]
self.history_index += 1

# This method returns the current value of the object
def get(self):
return self.history[self.history_index]

# This method undoes the last change to the object (if possible)
def undo(self):
if self.history_index > 0:
self.history_index -= 1
return self.history[self.history_index]

# This method redoes the last change to the object (if possible)
def redo(self):
if self.history_index < len(self.history) - 1:
self.history_index += 1
return self.history[self.history_index]