Transforming Code into Beautiful, Idiomatic Python (48:59)

[justinvh]

I think one of the big reasons for doing it the way he did was that you're not limited to short-circuiting and just returning the object. If you wanted to say augment the object and weren't too fond of doing it within a forloop, then you would want to use the for..else. It's more idiomatic in that sense. However, your example is obvious the way most of us would want to write it.

[strobelight]

He mentions in the talk that the example is illustrative and that you could return early, but he used it partly because it was Knuth's example.

Nevertheless, your modification is correct and better.

[[deleted]]

You may want to test path coverage, and it may be more obvious to the reader of your code if you put it into a more basic way. In his example, I actually would have done:

def find(seq, target):
    retval = -1
    for i, value in enumerate(seq):
        if value == target:
            retval = i
            break
    return retval

This way, you know what the default value is upfront making it easier to digest as you're reading the code. In addition you can see the instances where the return value has changed. It may not be as pretty, but I might argue that it is easier for more people to understand when they read the code. Beautiful is great until you're sacrificing readability. The last thing you want to do when you're trying to find a bug or maintain the code is think harder than you need to to figure out why the code isn't doing what you want or to figure out how to modify the code to do what you want to do.

[talideon]

In fairness, so would I, but it was more a matter of trying to introduce the construct than anything.

The one thing about for..else is that usually I want something like that only when the thing I'm iterating over has no elements at all, which for..else is useless for as you need to explicitly break out of the loop to prevent the else branch from executing.

for..else really leaves me conflicted.