The prefered Syntax for a typed named tuple since 3.6 is from typing import NamedTuple class Point(NamedTuple): x: int y: int = 1 # Set default value Point(3) # -> Point(x=3, y=1) Edit Starting Python 3.7, consider using dataclasses (your IDE may not yet support them for static type checking): from dataclasses import dataclass @dataclass … Read more
Use either the typing.TextIO or typing.BinaryIO types, for files opened in text mode or binary mode respectively. From the docs: class typing.IO Wrapper namespace for I/O stream types. This defines the generic type IO[AnyStr] and aliases TextIO and BinaryIO for respectively IO[str] and IO[bytes]. These representing the types of I/O streams such as returned by … Read more
For python 3.8 try: def f() -> “pd.Series[str]”: pass or: f_return_type = “pd.Series[str]” def f() -> f_return_type: pass or # type: pd.Series[str] for variables
Consider the following code: class Foo: def bar(self) -> Foo: return Foo() This program will actually crash at runtime if you try running it with Python: when the interpreter sees the definition of bar, the definition of Foo is not yet finished. So, since Foo has not yet been added to the global namespace, we … Read more
The name Foo isn’t bound yet, because the class itself has not yet been defined at the time that you try to use the name (remember: function arguments are evaluated at function definition time, not at function call time). From Python 3.7+ you can postpone evaluation of annotations by adding this import at the top … Read more
In PHP 7 they added the following: Type declarations allow functions to require that parameters are of a certain type at call time. If the given value is of the incorrect type, then an error is generated: in PHP 5, this will be a recoverable fatal error, while PHP 7 will throw a TypeError exception. … Read more
As of PHP 8+, you may use union types: function test(): FailObject|SuccessObject {} Another way, available in all versions since PHP 4, is for the two objects to share an interface. Example: interface ReturnInterface {} class FailObject implements ReturnInterface {} class SuccessObject implements ReturnInterface {} function test(): ReturnInterface {} In this example, ReturnInterface is empty. … Read more
Type hinting the Color class should work: def get_color_return_something(some_color: Color): print(some_color.value)
See the fifth paragraph of the abstract in the PEP you link to: While these annotations are available at runtime through the usual __annotations__ attribute, no type checking happens at runtime . Instead, the proposal assumes the existence of a separate off-line type checker which users can run over their source code voluntarily
The following answer only applies to Python < 3.9 The expression list[int] is attempting to subscript the object list, which is a class. Class objects are of the type of their metaclass, which is type in this case. Since type does not define a __getitem__ method, you can’t do list[…]. To do this correctly, you … Read more