How to detect typos in Python programs

David Bolen db3l at
Tue Jul 29 18:53:48 CEST 2003

Manish Jethani <manish.j at> writes:

> There's a difference between my "abost()" example and the "56"
> example.  There's no function called abost anywhere in the
> program text, so I should be able to detect the error with
> static analysis.  Even in C, the compiler warns about stray
> function calls.

But in your example, you were calling "session.abost".  Due to
Python's dynamic nature, there's no way for a static compile-time
analysis to know for sure if the object to which session (I'm guessing
it's a global from the code) refers _at the point when that code
executes_ has an abost method or not.  Or rather, no way I can see
other than having the compiler actually execute the code to determine
that fact.

Given that you want some specific behavior to occur on a close
connection event, you're really best served by having a test that
actually simulates such an event to verify that your action occurs.
That's true in any language, although particularly so in Python.  It's
certainly best to use automated tests, but even some manual setup for
more complicated network situations can help.  For example, if I were
writing such a system, I'd probably at least manually start up a
modified server that explicitly disconnected more frequently so I
could exercise that aspect of tear-down more easily.  Otherwise
(syntax checks or no), I'd be releasing code without really having any
idea that it would do the right thing in such a teardown situation.

Think of it just as another aspect to "good coding practices".

-- David

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