for / while else doesn't make sense

[Steven D'Aprano]

On Sat, 21 May 2016 05:20 am, Christopher Reimer wrote:

> According to "Effective Python: 59 Specific Ways to Write Better Python"
> by Brett Slatkin, Item 12 recommends against using the else block after
> for and while loops (see page 25): "Avoid using else blocks after loops
> because their behavior isn't intuitive and can be confusing."

By that logic, we ought to:

- avoid using floats because their behaviour isn't intuitive and
  can be confusing;
- avoid using lists because their behaviour isn't intuitive and
  can be confusing;
- avoid using classes because their behaviour isn't intuitive and
  can be confusing;
- avoid any form of asynchronous functions because their behaviour
  isn't intuitive and can be confusing;

and so on. I can give examples of unintuitive and confusing behaviour for
all of those things, and more, except the last. And the reason I can't give
examples for async programming is because it confuses me and I don't
understand it well enough to give even a minimal example.

Just about the only things in Python which are intuitive and not confusing
to somebody are None and ints.

Or, we can *learn how to use the features* and stop thinking that
programming is a matter of intuition. And most importantly, stop thinking
that features need to be judged entirely by the least knowledgeable
programmers.


> Until I read the book, I wasn't aware of this feature (or bug). Doesn't
> seem like a feature I would use since it's not commonly found in other
> programming languages. As the author demonstrates in his book, I would
> probably write a helper function instead.

Sorry, was that called "Ineffective Python"?

There is absolutely nothing effective about re-inventing the wheel badly or
writing unnecessary code.

Are you programming in those other languages or in Python? If you're
programming in, say, Javascript, I can completely understand you deciding
to limit yourself to features available in Javascript. Indeed to try to use
Python language features in Javascript would be an exercise in frustration.
Likewise using Ruby language features in Python is nothing but SyntaxError
after SyntaxError, it makes it hard to get work done.

But the idea that you should avoid a Python feature while programming in
Python because Javascript doesn't have it, or Ruby, or C, is surely the
height of muddleheaded thinking. You're not programming Javascript, Ruby or
C, you're programming in Python. The whole point of picking one language
over another is to get access to the tools and features that language
offers. Otherwise you're just wasting your time.



-- 
Steven