[cse491] Revised HW #1

[C. Titus Brown]

Hi folks,

I added two simple problems to the HW after realizing that I'd forgotten
to put them on in the first place; sorry for the addition.  The new
HW is attached (see bottom, addition of FibonacciListLike and
FibonacciDictLike).  I've also given a guideline or two: in particular,

	...elegance and speed of implementation are not a consideration;
	go for correctness and simplicity, *first*.

I've also posted this week's lab notes & homework on the Web site,

	http://ged.msu.edu/courses/2008-fall-cse-491/materials.html

cheers,
--titus
-- 
C. Titus Brown, ctb at msu.edu
-------------- next part --------------
Homework 1: Iterators and Generators
====================================

Due Thursday, Sep 4th, 12:40pm (just after noon).  Information on how to hand
it in TBD.

----

Create a Python file 'homework1' that contains the following objects:

  make_fib(n) -- a function that returns the first n elements in the Fibonacci
    series.

  FibonacciIterator(n) -- an iterator implementation of the Fibonacci
    series that generates the first n elements in the Fibonacci series.
    It should be non-reentrant, that is, __iter__ should return self.

  ReentrantFibonacciIterator(n) - a re-entrant version of the fib iterator,
    i.e. something that can be iterated over multiple times.

  fibonacci_generator(n) -- a generator implementation of the fib iterator.

  FibonacciListLike(max_n) -- a class that implements a dynamic list-like
    interface (through the sequence protocol), such that item 'i' is the
    i'th Fibonacci number, while i < 'max_n'.

  FibonacciDictLike(max_n) -- a class that implements a dynamic dict-like
    interface (through the mapping protocol) such that indexing with the
    key 'fibN' retrieves the Nth Fibonacci number.

Note: the list-like and dict-like interfaces can use the other classes
and functions, of course. Also, elegance and speed of implementation
are not a consideration; go for correctness and simplicity, *first*.

Your code should minimally pass the following tests: ::

    import homework1
    import types

    fib8 = [0, 1, 1, 2, 3, 5, 8, 13, 21]

    x = homework1.make_fib(8)
    assert fib8 == x

    x = homework1.FibonacciIterator(8)
    assert list(x) == fib8
    assert list(x) == []

    x = homework1.ReentrantFibonacciIterator(8)
    assert list(x) == list(x)
    assert list(x) == fib8

    x = homework1.fibonacci_generator(8)
    assert isinstance(x, types.GeneratorType)
    assert list(x) == fib8

    x = homework1.FibonacciListLike(9)
    assert x[0] == 0
    assert x[6] == 8
    assert fib8 == [ x[i] for i in range(0, 9) ]

    x = homework1.FibonacciDictLike(9)
    assert x['fib0'] == 0
    assert x['fib6'] == 8
    assert fib8 == [ x['fib%d' % (i,)] for i in range(0, 9) ]