Exceptions and control flow

Since exceptions are a means of control flow, they can be clumsy to demonstrate at the REPL, so in this chapter we'll be using a Python module to contain our code. Let's start with a very simple module we can use for exploring these important concepts and behaviors. Place the this code in a module called exceptional.py:

"""A module for demonstrating exceptions."""

def convert(s):
    """Convert to an integer."""
    x = int(s)
    return x

Import the convert() function from this module into the Python REPL:

$ python3
Python 3.5.1 (v3.5.1:37a07cee5969, Dec  5 2015, 21:12:44)
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from exceptional import convert

and call our function with a string to see that it has the desired effect:

>>> convert("33")
33

If we call our function with an object that can't be converted to an integer, we get a traceback from the int() call:

>&gt...