How to catch these kind of bugs in Python?

[dave.brueck at gmail.com]

asincero wrote:
> Is there anyway to catch the following type of bug in Python code:
>
> message = 'This is a message'
> if some_obscure_condition:
>    nessage = 'Some obscure condition occured.'
> print message
>
>
> In the above example, message should be set to 'Some obscure condition
> occured.' if some_obscure_condition is True.  But due to a lack of
> sleep, and possibly even being drunk, the programmer has mistyped
> message.  These types of bugs would easily be caught in languages that
> have a specific keyword or syntax for declaring variables before use.

There are tools that help (e.g. pychecker), but there are a few things
to consider:

1) If the programmer is sleepy/drunk, you're going to have other bugs
too (logical errors, not handling all cases, etc.)

2) Other languages would catch *some* types of these bugs, but would
still miss some of them (I can see a sleepy programmer also using the
wrong variable instead of just mistyping the right one).

So while a tool might assist, it's worth your while to also consider
some strategies for tackling the above two problems and, in the
process, the sleepy-programmer-mistype bugs will get caught as well.
Some type of testing is probably the best answer - be it reusable unit
tests or, at the very least, some interactive testing of code snippets
(which Python makes really easy to do).

-Dave