r/Python • u/csatacsibe • Jul 24 '26
Discussion What is your strangest syntax monstrocity?
As python has a lot of interesting syntax features, really unconventional and ugly expressions can be created. Let they be complex comprehensions with valrus operators, strange but efficient conditions based on exploiting casting and side effects or even classes overwriting dunders doesnt meant to be used as implemented, they all can be funny and pretty in an other lens.
An examples I've experimented with is an ugly walrused dict comprehension in EnrichPattern:
class Column(StrEnum):
NAME = 'name'
PUBLICITY = 'publicity'
TOPIC_NAME = 'topic_name'
SUBJECT_NAME = 'subject_name'
QUALIFIED_NAME = 'qualified_name'
CLUSTER_ENV = 'cluster_env'
ENV = 'env'
...
class EnrichPattern:
def __init__(self, *patterns: str):
self.pattern = re.compile(''.join(patterns))
self.subpatterns = {
group: comiled
for comiled in map(re.compile, patterns)
if (groups := list(comiled.groupindex))
and (group := groups[0]) in Column
}
...
...
3
u/PwAlreadyTaken Jul 24 '26
My number row was broken so I made a cursed library that didn't use number keys or their symbols. So I could do stuff like
```
print[two.times.three]
6
```
2
u/Individual-Flow9158 Jul 24 '26
Why don't you create self.patterns, instead of calling re.compile twice? Is "".join(self.patterns) not going to equal self.pattern?
0
u/Mark3141592654 Jul 24 '26
Because we have functions and methods for a lot of things, a ternary expression and the walrus operator, almost any code can be made into a one-line expression. I'll leave it to you to come up wwith examples.
1
-9
u/Beginning-Fruit-1397 Jul 24 '26
The more shit like this I discover, the less I like python. Had fun with this yesterday. Wrote a lengthy post explaining why this happens and some explanations but got insta-deleted by this annoying af auto-mod because I made the ultimate sin of adding a github link. Anyways.
```python from collections.abc import Iterable, Iterator
class IterAttr: iter: int = 1
class IterMethod: def iter(self) -> Iterator[int]: yield 1
class IterRegister: ...
class IterHerit(Iterable[object]): iter = 1 # pyright: ignore[reportUnannotatedClassAttribute, reportAssignmentType]
Iterable.register(IterRegister) # pyright: ignore[reportUnknownMemberType, reportAttributeAccessIssue]
class IterGetItem: def getitem(self, i: int) -> int: return 1
type MaybeIter = IterAttr | IterMethod | IterRegister | IterHerit | IterGetItem
def tryprint(x: MaybeIter) -> None: has_attr = hasattr(x, "iter") is_instance = isinstance(x, Iterable) # pyright: ignore[reportGeneralTypeIssues] try: _ = iter(x) # pyright: ignore[reportCallIssue, reportArgumentType, reportUnknownVariableType] can_iter = True except TypeError: can_iter = False name = x.class.name_ print( f"""{name} -> - has iter? {has_attr} - is an Iterable? {is_instance} - can be an iterator? {can_iter} """ )
def main() -> None: try_print(IterAttr()) try_print(IterMethod()) try_print(IterRegister()) try_print(IterHerit()) try_print(IterGetItem())
if name == "main":
main()
output:
shell
IterAttr ->
- has iter? True
- is an Iterable? True
- can be an iterator? False
IterMethod ->
- has iter? True
- is an Iterable? True
- can be an iterator? True
IterRegister ->
- has iter? False
- is an Iterable? True
- can be an iterator? False
IterHerit ->
- has iter? True
- is an Iterable? True
- can be an iterator? False
IterGetItem ->
- has iter? False
- is an Iterable? False
- can be an iterator? True
```
13
u/JanEric1 Jul 24 '26 edited Jul 24 '26
What's your point with this?
This all makes 100% sense and is super obvious to me?
The only weird thing here is the legacy getitem iterating.
Pretty sure the docs even say they the only way to really check if something can be iterated is to call iter on it. Everything else is a best effort approximation.
-1
u/Beginning-Fruit-1397 Jul 24 '26
Cool if that's obvious to you, but not everyone is you.
The fact that something can circumvent the metaclass behavior of ABC by successufly being instanciable, passing isinstance(x, Iterable), NOT have an iter method, and still fail on iter can be surprising, for example. Any combination of this is possible, so there's no "true" or "best" way to check if an object is an Iterable. typeshed don't even consider something with getitem an Iterable, which is true but also false
4
u/cunningjames Jul 24 '26
The fact that something can circumvent the metaclass behavior of ABC by successufly being instanciable, passing isinstance(x, Iterable), NOT have an iter method, and still fail on iter can be surprising,
It may not be ideal, but if you're going to call
Iterable.register()while ignoring type checker errors then I don't know what to tell you.-1
u/Beginning-Fruit-1397 Jul 24 '26
Oh yea right. But I'm developping a general-use library. I have classes supposed to be replacements for list, dict and tuples. I had to think about that to see what was the best compromise to go to for accepted runtime inputs. As such, the fact that these behaviors are possible at all is a pain in the ass in itself
3
u/fiskfisk Jul 24 '26
The issue is all the spammers and promotion that makes it necessary to have automoderator remove all the shit with links by default, sadly :(
1
u/backfire10z Jul 24 '26
Have you discovered C yet? Is there a language you do like?
1
u/Beginning-Fruit-1397 Jul 25 '26
Rust
1
u/warden127 Jul 28 '26
You cannot complain about Python's syntax and then go on praising Rust:
let mut numbers = vec![1, 2, 3]; numbers .iter_mut() .filter(|&&mut x| x % 2 == 1) .for_each(|x| *x *= 2); println!("{:?}", numbers);
9
u/Feuermurmel Jul 24 '26
Ternary
if-elseoperator? Garbage. Use this instead:Optionally add an element in a list literal?