From 02a9ab542492ae6f36c507501dc1a9d3ba927a56 Mon Sep 17 00:00:00 2001
From: Marshal Newrock <newrockm@cse.msu.edu>
Date: Tue, 22 Jan 2013 12:23:07 -0500
Subject: [PATCH 1/4] fixed the bug

---
 iter_bug/fib.py  | 2 +-
 iter_bug/test.py | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/iter_bug/fib.py b/iter_bug/fib.py
index 59a39a4..03e0d38 100644
--- a/iter_bug/fib.py
+++ b/iter_bug/fib.py
@@ -12,5 +12,5 @@ def __iter__(self):
 
     def next(self):
         next_fib = self.last_1 + self.last_2
-        self.last_1, self.last2 = self.last_2, next_fib
+        self.last_1, self.last_2 = self.last_2, next_fib
         return next_fib
diff --git a/iter_bug/test.py b/iter_bug/test.py
index db32b46..2740f33 100644
--- a/iter_bug/test.py
+++ b/iter_bug/test.py
@@ -11,7 +11,7 @@ def test2():
     i.next()
     assert i.next() == 3
 
-def test2():
+def test3():
     f = fib.fib()
     i = iter(f)
     i.next()

From d1f1995529892782d650cfbf0c3299c70f1a001d Mon Sep 17 00:00:00 2001
From: Marshal Newrock <newrockm@cse.msu.edu>
Date: Thu, 24 Jan 2013 11:53:25 -0500
Subject: [PATCH 2/4] Look up in the sky...it's a module, it's a generator,
 it's an iterator...it's sieve!

---
 sieve_gen/example.py  | 10 ++++++++++
 sieve_gen/sieve.py    | 18 ++++++++++++++++++
 sieve_iter/example.py | 10 ++++++++++
 sieve_iter/sieve.py   | 23 +++++++++++++++++++++++
 sieve_mod/example.py  |  5 +++++
 sieve_mod/sieve.py    | 19 +++++++++++++++++++
 6 files changed, 85 insertions(+)
 create mode 100644 sieve_gen/example.py
 create mode 100644 sieve_gen/sieve.py
 create mode 100644 sieve_iter/example.py
 create mode 100644 sieve_iter/sieve.py
 create mode 100644 sieve_mod/example.py
 create mode 100644 sieve_mod/sieve.py

diff --git a/sieve_gen/example.py b/sieve_gen/example.py
new file mode 100644
index 0000000..3b18a58
--- /dev/null
+++ b/sieve_gen/example.py
@@ -0,0 +1,10 @@
+import sieve
+
+count = 1
+
+for n in sieve.primes():
+    print n
+    count += 1
+    if count > 10:
+        break
+
diff --git a/sieve_gen/sieve.py b/sieve_gen/sieve.py
new file mode 100644
index 0000000..91a6c82
--- /dev/null
+++ b/sieve_gen/sieve.py
@@ -0,0 +1,18 @@
+# an implementation of Eratosthenes' Sieve as a generator
+
+def _is_prime(primes, n):
+    for i in primes:
+        if n % i == 0:
+            return False
+    return True
+
+def primes():
+    primeslist = [2]
+    start = primeslist[-1] + 1
+    while 1:
+        if _is_prime(primeslist, start):
+            primeslist.append(start)
+            yield start
+
+        start += 1
+
diff --git a/sieve_iter/example.py b/sieve_iter/example.py
new file mode 100644
index 0000000..3b18a58
--- /dev/null
+++ b/sieve_iter/example.py
@@ -0,0 +1,10 @@
+import sieve
+
+count = 1
+
+for n in sieve.primes():
+    print n
+    count += 1
+    if count > 10:
+        break
+
diff --git a/sieve_iter/sieve.py b/sieve_iter/sieve.py
new file mode 100644
index 0000000..45cb5c8
--- /dev/null
+++ b/sieve_iter/sieve.py
@@ -0,0 +1,23 @@
+# an implementation of Eratosthenes' Sieve as an iterator
+
+class primes(object):
+    def __init__(self):
+        self.primeslist = [2]
+        self.start = self.primeslist[-1] + 1
+
+    def __iter__(self):
+        return self
+
+    def _is_prime(self, n):
+        for i in self.primeslist:
+            if n % i == 0:
+                return False
+        return True
+
+    def next(self):
+        while 1:
+            if self._is_prime(self.start):
+                self.primeslist.append(self.start)
+                return self.start
+            self.start += 1
+
diff --git a/sieve_mod/example.py b/sieve_mod/example.py
new file mode 100644
index 0000000..01c65f3
--- /dev/null
+++ b/sieve_mod/example.py
@@ -0,0 +1,5 @@
+import sieve
+
+for n in range(10):
+    print sieve.next()
+
diff --git a/sieve_mod/sieve.py b/sieve_mod/sieve.py
new file mode 100644
index 0000000..13b0408
--- /dev/null
+++ b/sieve_mod/sieve.py
@@ -0,0 +1,19 @@
+# an implementation of Eratosthenes' Sieve in a module
+
+_primeslist = [2]
+
+def _is_prime(primes, n):
+    for i in primes:
+        if n % i == 0:
+            return False
+    return True
+
+def next():
+    start = _primeslist[-1] + 1
+    while 1:
+        if _is_prime(_primeslist, start):
+            _primeslist.append(start)
+            return start
+
+        start += 1
+

From 3dd5d9f349e2b00a0a6207045e81546fc06c6ba3 Mon Sep 17 00:00:00 2001
From: Marshal Newrock <newrockm@cse.msu.edu>
Date: Thu, 24 Jan 2013 12:10:23 -0500
Subject: [PATCH 3/4] Fix bug omitting 2 as the first prime

---
 sieve_gen/sieve.py  | 4 ++++
 sieve_iter/sieve.py | 8 ++++++--
 sieve_mod/sieve.py  | 8 +++++++-
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/sieve_gen/sieve.py b/sieve_gen/sieve.py
index 91a6c82..1a2ea4d 100644
--- a/sieve_gen/sieve.py
+++ b/sieve_gen/sieve.py
@@ -7,7 +7,11 @@ def _is_prime(primes, n):
     return True
 
 def primes():
+    # first iteration, return 2 as the first prime number
     primeslist = [2]
+    yield 2
+
+    # subsequent iterations build off of previously determined primes
     start = primeslist[-1] + 1
     while 1:
         if _is_prime(primeslist, start):
diff --git a/sieve_iter/sieve.py b/sieve_iter/sieve.py
index 45cb5c8..5127032 100644
--- a/sieve_iter/sieve.py
+++ b/sieve_iter/sieve.py
@@ -2,8 +2,7 @@
 
 class primes(object):
     def __init__(self):
-        self.primeslist = [2]
-        self.start = self.primeslist[-1] + 1
+        self.primeslist = []
 
     def __iter__(self):
         return self
@@ -15,6 +14,11 @@ def _is_prime(self, n):
         return True
 
     def next(self):
+        if len(self.primeslist) == 0:
+            self.primeslist.append(2)
+            return 2
+
+        self.start = self.primeslist[-1] + 1
         while 1:
             if self._is_prime(self.start):
                 self.primeslist.append(self.start)
diff --git a/sieve_mod/sieve.py b/sieve_mod/sieve.py
index 13b0408..bdd1290 100644
--- a/sieve_mod/sieve.py
+++ b/sieve_mod/sieve.py
@@ -1,6 +1,6 @@
 # an implementation of Eratosthenes' Sieve in a module
 
-_primeslist = [2]
+_primeslist = []
 
 def _is_prime(primes, n):
     for i in primes:
@@ -9,6 +9,12 @@ def _is_prime(primes, n):
     return True
 
 def next():
+    # first iteration, add 2 as a prime number
+    if len(_primeslist) == 0:
+        _primeslist.append(2)
+        return 2
+
+    # subsequent iterations build off of the previously determined list
     start = _primeslist[-1] + 1
     while 1:
         if _is_prime(_primeslist, start):

From 8f2cfc006afe7905ef0e3097c71b11ad92c15c5c Mon Sep 17 00:00:00 2001
From: Marshal Newrock <newrockm@cse.msu.edu>
Date: Thu, 24 Jan 2013 12:17:38 -0500
Subject: [PATCH 4/4] Add generator and iterator tests

---
 sieve_gen/test1.py  |  6 ++++++
 sieve_gen/test2.py  |  9 +++++++++
 sieve_gen/test3.py  | 10 ++++++++++
 sieve_iter/test1.py |  6 ++++++
 sieve_iter/test2.py |  9 +++++++++
 sieve_iter/test3.py | 10 ++++++++++
 6 files changed, 50 insertions(+)
 create mode 100644 sieve_gen/test1.py
 create mode 100644 sieve_gen/test2.py
 create mode 100644 sieve_gen/test3.py
 create mode 100644 sieve_iter/test1.py
 create mode 100644 sieve_iter/test2.py
 create mode 100644 sieve_iter/test3.py

diff --git a/sieve_gen/test1.py b/sieve_gen/test1.py
new file mode 100644
index 0000000..5cbb624
--- /dev/null
+++ b/sieve_gen/test1.py
@@ -0,0 +1,6 @@
+import sieve
+
+# test 1 - the first prime should be 2
+gen = sieve.primes()
+assert gen.next() == 2
+
diff --git a/sieve_gen/test2.py b/sieve_gen/test2.py
new file mode 100644
index 0000000..de56be0
--- /dev/null
+++ b/sieve_gen/test2.py
@@ -0,0 +1,9 @@
+import sieve
+
+# test 2 - the fourth prime should be 7 - happy :)
+gen = sieve.primes()
+gen.next()
+gen.next()
+gen.next()
+assert gen.next() == 7
+
diff --git a/sieve_gen/test3.py b/sieve_gen/test3.py
new file mode 100644
index 0000000..8fd00af
--- /dev/null
+++ b/sieve_gen/test3.py
@@ -0,0 +1,10 @@
+import sieve
+
+# test 3 - there are 10 primes less than 30
+count = 0
+gen = sieve.primes()
+while gen.next() < 30:
+    count += 1
+
+assert count == 10
+
diff --git a/sieve_iter/test1.py b/sieve_iter/test1.py
new file mode 100644
index 0000000..5cbb624
--- /dev/null
+++ b/sieve_iter/test1.py
@@ -0,0 +1,6 @@
+import sieve
+
+# test 1 - the first prime should be 2
+gen = sieve.primes()
+assert gen.next() == 2
+
diff --git a/sieve_iter/test2.py b/sieve_iter/test2.py
new file mode 100644
index 0000000..de56be0
--- /dev/null
+++ b/sieve_iter/test2.py
@@ -0,0 +1,9 @@
+import sieve
+
+# test 2 - the fourth prime should be 7 - happy :)
+gen = sieve.primes()
+gen.next()
+gen.next()
+gen.next()
+assert gen.next() == 7
+
diff --git a/sieve_iter/test3.py b/sieve_iter/test3.py
new file mode 100644
index 0000000..8fd00af
--- /dev/null
+++ b/sieve_iter/test3.py
@@ -0,0 +1,10 @@
+import sieve
+
+# test 3 - there are 10 primes less than 30
+count = 0
+gen = sieve.primes()
+while gen.next() < 30:
+    count += 1
+
+assert count == 10
+