What is the correct syntax for a Python function/method argument when it has more than one possible type hints? Question: import os def scan(path) -> os.DirEntry : return os.scandir(path) What is the correct type hint for the path argument of this function? According to documentation: path may be a path-like object. If path is of …
How to alias a type used in a class before it is declared? Question: I have code similar to this example import typing class C(): def __init__(self, callback: typing.Callable[[C], int]): self._callback = callback def getCallback() -> typing.Callable[[C], int]: return self._callback class C2(): def __init__(self, cInstance: C): self._cInstance = cInstance def f() -> typing.NoReturn: self._cInstance.getCallback()(self.cInstance) and …
Type hints support for subclass of dict Question: How can I implement a subclass of dict so it supports type hints like vanilla dict? I want to create a custom dict that does some extra work when modifying item, I implement it by subclassing the built-in dict class. After doing some googling I learned that …
How to make mypy like my protocols that work at runtime with runtime_checkable Question: I defined a couple of protocols like so: import json from typing import Any, Protocol, TypeVar, runtime_checkable T_co = TypeVar(‘T_co’, covariant=True) T = TypeVar(‘T’) @runtime_checkable class SupportsRead(Protocol[T_co]): def read(self, __length: int = …) -> T_co: … @runtime_checkable class SupportsWrite(Protocol[T_co]): def write(self, …
How to return a anonymous NamedTuple in python defined only in the return type hint Question: I come from Typescript, new to Python. When I have 2 things to return from a function and I only use these 2 keys for that function return type and nowhere else in the code, I don’t create a …
Overload type hint with Literal and Enum not working in PyCharm Question: I want to typehint an overload function. For that I use the overload decorator from typing. I want to set multiple possible callees based on a parameter’s value. This parameter is color. I have this code: from typing import Literal, overload from enum …
How do I type hint for Enums in Python? Question: I have a python function for which I want to use type hinting. There are two arguments. The first is any Enum class, the second optional arg is an element of that Enum. For example, say I have: class Foo(Enum): ALPHA = 1 BETA = …
Type hints for the generic utility in the Django Question: def get_or_create_object(self, model : ?(what will be the type?), data: dict) -> ? (what will be the return type): try: obj, _ = model.objects.get_or_create(**data) except model.MultipleObjectsReturned: obj = model.objects.filter(**data).first() return obj get_or_create_object(ModelName, data) What will be the type hint here – as function will get …
type hint for generic attribute inside abstract class Question: I have a convoluted problem with types that I can´t solve. Let’s say I have some abstract classes and a generic type equivalent to this from abc import ABC from typing import Generic, TypeVar class Action(ABC): pass ActionTypeVar = TypeVar("ActionTypeVar", bound="Action") class Agent(ABC, Generic[ActionTypeVar]): actions: tuple[ActionTypeVar, …
Specify return type of a wrapper function that calls an abstract method in Python Question: For this example, consider the simplified scenario where a Solver will return a Solution. We have Solutions: class Solution(ABC): pass class AnalyticalSolution(Solution): pass class NumericalSolution(Solution): def get_mesh_size(self) -> float: return 0.12345 And Solvers: class Solver(ABC): def solve(self, task: int) -> …
