Thursday, November 11, 2010

Python 'not callable' errors

Be careful not to heist the names of methods in

The python language allows you to dynamically redefine a method to a variable, and vice-versa. This can be a nice feature if you do it intentionally. But it can be a nuisance to debug if unintentional. Here is a quick example:

First, define a method which returns the sum of two numbers:

ding@dingp:~$ python
Python 2.5.2 (r252:60911, Jan 20 2010, 21:48:48)
[GCC 4.2.4 (Ubuntu 4.2.4-1ubuntu3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> def myMethod(i,j):
... return i+j

Pass in two numbers, set the return value to another variable, and it works as expected.

>>> k = myMethod(1,2)
>>> print k

But watch what happens next...