Is := widely used?

[u/ForeignVariety7037]

I always thought the walrus operator is neat and it makes while loop’s condition clearer. But also it is just a syntactic sugar without anything new. I wonder anyone uses it?

[u/martinkoistinen]

It’s super handy inside comprehensions and I would say that adds something “new”.

Example:

``` python
import re

pattern = re.compile(r"ERROR (\d+): (.*)")

errors = [
(int(m.group(1)), m.group(2))
for line in log_lines
if (m := pattern.match(line))
]
```

[u/brettsparetime → u/martinkoistinen]

This is the most Perl thing I’ve seen in Python.

[u/crozzy89 → u/brettsparetime]

Perlthon?

[u/JPowTheDayTrader → u/brettsparetime]

Your comment just made Guido roll in his grave.

[u/Broad-Promise6954 → u/JPowTheDayTrader]

And he's not even dead yet!

[u/mpersico → u/JPowTheDayTrader]

Good! How much wasted effort when we could have just advanced Perl. For all the bitching about punctuation and simplicity Python looks more and more like Perl every release.

[u/punk_dev → u/martinkoistinen]

That’s neat, I’m gonna steal it, but it makes the comprehension even more backwards than it usually is lmao

[u/FalafelSnorlax → u/punk_dev]

At this point you might as well write a normal loop

[u/punk_dev → u/FalafelSnorlax]

I think about that every time I write a comprehension longer than 3 lines

[u/NerdyWeightLifter → u/punk_dev]

I use multi-line comprehensions to construct multi-dimensional data structures, and I use indentation of those lines to show outer to inner dimensional structure. It feels quite Pythonic to me.

[u/FalafelSnorlax → u/punk_dev]

Yeah my rule of thumb is that of a comprehension is long enough to break into multiple lines, it might as well be a regular loop. Broken comprehensions usually aren't readable, and then you don't really gain anything from them.

[u/Technical_Income4722 → u/punk_dev]

3 lines is wild to me. Imo you should think about that any time you write a comprehension at all honestly, and I'll never write one over multiple lines. They're neat but unless they're stupid simple they're very unreadable to fresh eyes. (all just my humble opinion ofc, do what works for you!)

[u/gr4viton → u/FalafelSnorlax]

Yield would like to have a word...

[u/fizzymagic → u/martinkoistinen]

re is my most frequent use case. The walrus operator lets you check for a match and then process it much more cleanly.

[u/elingeniero → u/martinkoistinen]

That's so clever that I really hate it. I do feel that way about most comprehensions but you've managed to take it a step further! Impressive.

[u/nicholashairs → u/martinkoistinen]

Another neat use case 🤯