diff --git a/assets/slides/14-Inheritance.pdf b/assets/slides/14-Inheritance.pdf
new file mode 100644
index 000000000..3c41ee8fa
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diff --git a/assets/slides/14.py b/assets/slides/14.py
new file mode 100644
index 000000000..8b77c760c
--- /dev/null
+++ b/assets/slides/14.py
@@ -0,0 +1,97 @@
+# Tracking Instances
+
+class Transaction:
+ """A logged transaction.
+
+ >>> s = [20, -3, -4]
+ >>> ts = [Transaction(x) for x in s]
+ >>> ts[1].balance()
+ 17
+ >>> ts[2].balance()
+ 13
+ """
+ log = []
+
+ def __init__(self, amount):
+ self.amount = amount
+ self.prior = list(self.log)
+ self.log.append(self)
+
+ def balance(self):
+ return self.amount + sum([t.amount for t in self.prior])
+
+class Account:
+ """An account has a balance and a holder.
+
+ >>> a = Account('John')
+ >>> a.holder
+ 'John'
+ >>> a.deposit(100)
+ 100
+ >>> a.withdraw(90)
+ 10
+ >>> a.withdraw(90)
+ 'Insufficient funds'
+ >>> a.balance
+ 10
+ >>> a.interest
+ 0.02
+ """
+
+ interest = 0.02 # A class attribute
+
+ def __init__(self, account_holder):
+ self.holder = account_holder
+ self.balance = 0
+
+ def deposit(self, amount):
+ """Add amount to balance."""
+ self.balance = self.balance + amount
+ return self.balance
+
+ def withdraw(self, amount):
+ """Subtract amount from balance if funds are available."""
+ if amount > self.balance:
+ return 'Insufficient funds'
+ self.balance = self.balance - amount
+ return self.balance
+
+
+class CheckingAccount(Account):
+ """A bank account that charges for withdrawals.
+
+ >>> ch = CheckingAccount('Jack')
+ >>> ch.balance = 20
+ >>> ch.withdraw(5)
+ 14
+ >>> ch.interest
+ 0.01
+ """
+
+ withdraw_fee = 1
+ interest = 0.01
+
+ def withdraw(self, amount):
+ return Account.withdraw(self, amount + self.withdraw_fee)
+ # Alternatively:
+ return super().withdraw(amount + self.withdraw_fee)
+
+# Multiple Inheritance
+
+class SavingsAccount(Account):
+ """A bank account that charges for deposits."""
+
+ deposit_fee = 2
+
+ def deposit(self, amount):
+ return Account.deposit(self, amount - self.deposit_fee)
+
+
+class AsSeenOnTVAccount(CheckingAccount, SavingsAccount):
+ """A bank account that charges for everything."""
+
+ def __init__(self, account_holder):
+ self.holder = account_holder
+ self.balance = 1 # A free dollar!
+
+supers = [c.__name__ for c in AsSeenOnTVAccount.mro()]
diff --git a/assets/slides/15-Linked_Lists.pdf b/assets/slides/15-Linked_Lists.pdf
new file mode 100644
index 000000000..759bc021c
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diff --git a/assets/slides/15.py b/assets/slides/15.py
new file mode 100644
index 000000000..b02e1a75c
--- /dev/null
+++ b/assets/slides/15.py
@@ -0,0 +1,64 @@
+class Link:
+ """A linked list.
+
+ >>> s = Link(3, Link(4, Link(5)))
+ >>> s
+ Link(3, Link(4, Link(5)))
+ >>> print(s)
+ <3 4 5>
+ >>> s.first
+ 3
+ >>> s.rest
+ Link(4, Link(5))
+ >>> s.rest.first
+ 4
+ >>> s.rest.first = 7
+ >>> s
+ Link(3, Link(7, Link(5)))
+ >>> s.first = 6
+ >>> s.rest.rest = Link.empty
+ >>> s
+ Link(6, Link(7))
+ >>> print(s)
+ <6 7>
+ >>> print(s.rest)
+ <7>
+ >>> t = Link(1, Link(Link(2, Link(3)), Link(4)))
+ >>> t
+ Link(1, Link(Link(2, Link(3)), Link(4)))
+ >>> print(t)
+ <1 <2 3> 4>
+ """
+ empty = ()
+
+ def __init__(self, first, rest=empty):
+ assert rest is Link.empty or isinstance(rest, Link)
+ self.first = first
+ self.rest = rest
+ #Not in scope!
+ def __repr__(self):
+ if self.rest:
+ rest_repr = ', ' + repr(self.rest)
+ else:
+ rest_repr = ''
+ return 'Link(' + repr(self.first) + rest_repr + ')'
+ #Not in scope!
+ def __str__(self):
+ string = '<'
+ while self.rest is not Link.empty:
+ string += str(self.first) + ' '
+ self = self.rest
+ return string + str(self.first) + '>'
+
+def map_link(f, s):
+ """Return a linked list of f(x) for each x in s.
+
+ >>> evens = Link(4, Link(2, Link(6)))
+ >>> map_link(lambda x: x + 1, evens)
+ Link(5, Link(3, Link(7)))
+ >>> evens
+ Link(4, Link(2, Link(6)))
+ """
+ if s is Link.empty:
+ return s
+ return Link(f(s.first), map_link(f, s.rest))
diff --git a/index.html b/index.html
index 1666a8a9e..8de984905 100644
--- a/index.html
+++ b/index.html
@@ -1071,6 +1071,8 @@
|
@@ -1133,6 +1135,8 @@
|
@@ -1142,10 +1146,10 @@
|
-Disc 08: Linked Lists
+Disc 08: Linked Lists
@@ -1571,7 +1575,7 @@
});
- let build_time = new Date(1000 * 1729541054.131282);
+ let build_time = new Date(1000 * 1729545120.543286);
|