Python Tip: Conditional Expressions

I learned something new today about Python 2.5 and newer. I thought it was so nifty that I decided to write a blog article about it. Hopefully someone out there finds it as interestingly useful as I do.

One of the things I find myself doing quite often in my code (be it Python, PHP, Java, or what have you) is a simple conditional assignment like so:

if foo:
    bar = 'baz'
else:
    bar = 'qux'

In a lot of languages these days, you can use a ternary operator as follows to turn these four lines into a one-liner:

<?php
$bar = $foo ? 'baz' : 'qux';
?>

However, this ternary operator does not exist in Python. I have used various means in the past to accomplish the same task without using code like we saw in the first code block above, but they were all very hackish. Today I was happy to learn that there is an official way to do it in Python:

bar = ('baz' if foo else 'qux')

I'm not sure which one is more confusing to newbies: Python's conditional expressions or other languages' ternary operator. Personally, I prefer constructs like these to make my code more concise. I my mind, they also make the code more readable. I have heard some folks argue that ternary operators and the like obfuscate the code more than necessary, so they discourage the use of such tactics and recommend using the classic approach featured in the first example.

For those who are interested, I learned about it and a few other neat things in Python 2.5 and newer at http://www.python.org/doc/2.5/whatsnew/pep-308.html.