12.8. Debugging

Python has some simple and rudimentary built-in documentation that can be quite helpful if you need a quick refresher to trigger your memory about the exact name of a particular method. This documentation can be viewed in the Python interpreter in interactive mode.

You can bring up an interactive help system using help().

>>> help()

help> modules

If you know what module you want to use, you can use the dir() command to find the methods in the module as follows:

import re
dir(re)
[.. 'compile', 'copy_reg', 'error', 'escape', 'findall',
'finditer', 'match', 'purge', 'search', 'split', 'sre_compile',
'sre_parse', 'sub', 'subn', 'sys', 'template']

11-9-1: Which of these options will find the methods of the time library?

• dir(time)
• Correct! The dir() command helps to find the methods of a given module.
• import time
• This will import the time module.
• help(time)
• This will not work.

You can also get a small amount of documentation on a particular method using the dir command.

help (re.search)
Help on function search in module re:

search(pattern, string, flags=0)
    Scan through string looking for a match to the pattern, returning
    a match object, or None if no match was found.

The built-in documentation is not very extensive, but it can be helpful when you are in a hurry or don’t have access to a web browser or search engine.

Fix the regex equation so that the code matches any dollar sign ($) followed by an integer or float.

import re x = 'The apples cost $9.99, whereas the bananas were only $5 and the oranges were $2.50 each.' y = re.findall('$[0_9\.]', x) ==== from unittest.gui import TestCaseGui class MyTests(TestCaseGui): def testOne(self): self.assertEqual(y, ['$9.99', '$5', '$2.50'], "Testing that the regex equation matches the proper parts of the string.") MyTests().main()

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