From 4633890289e83d52b733993c0c313d00f9166394 Mon Sep 17 00:00:00 2001
From: Crista Lopes <crista@tagide.com>
Date: Fri, 27 Sep 2013 12:01:14 -0700
Subject: [PATCH] Added style #22

---
 22-declared-intentions/README.md | 18 ++++++++
 22-declared-intentions/tf-22.py  | 72 ++++++++++++++++++++++++++++++++
 2 files changed, 90 insertions(+)
 create mode 100644 22-declared-intentions/README.md
 create mode 100644 22-declared-intentions/tf-22.py

diff --git a/22-declared-intentions/README.md b/22-declared-intentions/README.md
new file mode 100644
index 0000000..8107278
--- /dev/null
+++ b/22-declared-intentions/README.md
@@ -0,0 +1,18 @@
+Style #22
+==============================
+
+Constraints:
+
+- Existence of a run-time typechecker
+
+- Procedures and functions declare what types of arguments they expect
+
+- If callers send arguments of types that are't expected, the
+  procedures/functions are not executed
+
+
+Possible names:
+
+- declared intentions
+- "You've been warned!"
+
diff --git a/22-declared-intentions/tf-22.py b/22-declared-intentions/tf-22.py
new file mode 100644
index 0000000..4ff79f4
--- /dev/null
+++ b/22-declared-intentions/tf-22.py
@@ -0,0 +1,72 @@
+#!/usr/bin/env python
+
+import sys, re, operator, string, inspect
+
+#
+# Decorator for enforcing types of arguments in method calls
+#
+class AcceptTypes():
+    def __init__(self, *args):
+        self._args = args
+
+    def __call__(self, f):
+        def wrapped_f(*args):
+            for i in range(len(self._args)):
+                if type(args[i]) <> self._args[i]:
+                    raise TypeError("Expecting %s got %s" % (str(self._args[i]), str(type(args[i]))))
+
+            return f(*args)
+        return wrapped_f
+#
+# The functions
+#
+@AcceptTypes(str)
+def extract_words(path_to_file):
+    """
+    Takes a path to a file and returns the non-stop
+    words, after properly removing nonalphanumeric chars
+    and normalizing for lower case
+    """
+    with open(path_to_file) as f:
+        str_data = f.read()
+    
+    pattern = re.compile('[\W_]+')
+    word_list = pattern.sub(' ', str_data).lower().split()
+
+    with open('../stop_words.txt') as f:
+        stop_words = f.read().split(',')
+
+    stop_words.extend(list(string.ascii_lowercase))
+    return [w for w in word_list if not w in stop_words]
+
+@AcceptTypes(list)
+def frequencies(word_list):
+    """
+    Takes a list of words and returns a dictionary associating
+    words with frequencies of occurrence
+    """
+    word_freqs = {}
+    for w in word_list:
+        if w in word_freqs:
+            word_freqs[w] += 1
+        else:
+            word_freqs[w] = 1
+    return word_freqs
+
+@AcceptTypes(dict)
+def sort(word_freq):
+    """
+    Takes a dictionary of words and their frequencies
+    and returns a list of pairs where the entries are
+    sorted by frequency 
+    """
+    return sorted(word_freq.iteritems(), key=operator.itemgetter(1), reverse=True)
+
+#
+# The main function
+#
+word_freqs = sort(frequencies(extract_words(sys.argv[1])))
+
+for tf in word_freqs[0:25]:
+    print tf[0], ' - ', tf[1]
+