hw10.py (plain text)

"""CS 61A HW 10
Name:
Login:
TA:
Section:
"""


#### Core Questions
#### Q0
"""Draw environment diagrams for each set of doctests below.  Turn these in on
paper.
"""


#### Q1
def make_account(balance):
    """Make a bank account dispatch function.

    >>> tom_acct = make_account(100)
    >>> tom_acct('balance')
    100
    >>> tom_acct('deposit', 20)
    >>> tom_acct('balance')
    120
    >>> tom_acct('withdraw', 30)
    >>> tom_acct('balance')
    90
    """
    def account(msg, *args):
        "*** YOUR CODE HERE ***"
    return account


#### Q2
"""Draw the environment diagram for the following doctest.

>>> x = [1, 2, 3]
>>> def foobar(y):
...     y[1] = x
...
>>> foobar(x)
>>> z = x[1]
>>> z[0] = 5
>>> x[0]
5
>>> x[1] = 33
>>> def map(fn, lst):
...     for i in range(len(lst)):
...         lst[i] = fn(lst[i])
... 
>>> map(lambda x: x + z[2], x)
>>> x
[8, 36, 6]
"""

#### Reinforcement Questions
#### Q3
def make_advanced_counter_maker():
    """Makes a function that makes counters that understands the messages
    "count", "global-count", "reset", and "global-reset".  See the examples
    below:

    >>> make_counter = make_advanced_counter_maker()
    >>> tom_counter = make_counter()
    >>> tom_counter('count')
    1
    >>> tom_counter('count')
    2
    >>> tom_counter('global-count')
    1
    >>> jon_counter = make_counter()
    >>> jon_counter('global-count')
    2
    >>> jon_counter('count')
    1
    >>> jon_counter('reset')
    >>> jon_counter('count')
    1
    >>> tom_counter('count')
    3
    >>> jon_counter('global-count')
    3
    >>> jon_counter('global-reset')
    >>> tom_counter('global-count')
    1
    """
    "*** YOUR CODE HERE ***"


#### Q4
def make_miss_manners(dispatch):
    """Makes a new dispatch function that uses the old dispatch function
    whenever you give it the message "please <action>"

    >>> def make_counter():
    ...     count = 0
    ...     def counter(msg):
    ...         nonlocal count
    ...         if msg == "count":
    ...             count += 1
    ...             return count
    ...         print("Sorry, I don't know how to " + msg)
    ...     return counter
    ...
    >>> manners_counter = make_miss_manners(make_counter())
    >>> manners_counter("count")
    You must say please!
    >>> manners_counter("please count")
    1
    >>> manners_counter("count")
    You must say please!
    >>> manners_counter("please count")
    2
    """
    "*** YOUR CODE HERE ***"


#### Extra for Experts
"""There is no Extra for Experts in this homework.  Go study for the exam."""