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) ]