Exercises in Programming Style

Chapter 21

Tantrum

21.1 Constraints

• Every single procedure and function checks the sanity of its arguments and refuses to continue when the arguments are unreasonable.
• All code blocks check for all possible errors, possibly log context-specific messages when errors occur, and pass the errors up the function call chain.

21.2 A Program in this Style

  1 #!/usr/bin/env python
  2
  3 import sys, re, operator, string, traceback
  4
  5 #
  6 # The functions
  7 #
  8 def extract_words(path_to_file):
  9 assert(type(path_to_file) is str), "I need a string!"
 10 assert(path_to_file), "I need a non-empty string!"
 11
 12 try:
 13  with open(path_to_file) as f:
 14 str_data ...