Exercises in Programming Style

Chapter 12

Closed Maps

12.1 Constraints

• The larger problem is decomposed into things that make sense for the problem domain.
• Each thing is a map from keys to values. Some values are procedures/functions.
• The procedures/functions close on the map itself by referring to its slots.

12.2 A Program in this Style

  1 #!/usr/bin/env python
  2 import sys, re, operator, string
  3
  4 # Auxiliary functions that can't be lambdas
  5 #
  6 def extract_words(obj, path_to_file):
  7 with open(path_to_file) as f:
  8  obj['data'] = f.read()
  9 pattern = re.compile('[\W_]+')
 10 data_str = ''.join(pattern.sub(' ', obj['data']).lower())
 11 obj['data'] = data_str.split()