CODEWITHSUNDEEP
pythongenerics
J'e
J'e

Reputation: 3726

python enforce type hints

How do I use enforce_typing with typing.Generic?

basic usage of enforce_typing looks like this and works as expected,

from enforce_typing import enforce_types

@enforce_types
def bar(val : float) -> None:
    print(val)
    
bar(3.14) # PASS
bar('3.14') # TypeError: Expected type '<class 'float'>' for attribute 'val' but received type '<class 'str'>')

I'm trying to use enfore_typing with a generic class (templated). The following code results in TypeError: isinstance() arg 2 must be a type or tuple of types. How can I use enforce_typing with a templated class?

from enforce_typing import enforce_types
from typing import TypeVar, Generic
T = TypeVar('T')

class Foo(Generic[T]):
    @enforce_types
    def __init__(self, value: T) -> None:
        self.value = value

    @property
    def val(self) -> T:
        return self.value
    
foo = Foo[float](3.14)

Upvotes: 1

Views: 1124

Answers (1)

agtoever
agtoever

Reputation: 1699

Your enforce_typing library (source) seems outdated.

Since Python 3.5, Python supports the typing library, that allows for type hints.

Using a type checker, such as mypy, you can check if typing hints are provided in all times (using the option --strict).

I recommend using Python version 3.5 or later, use the typing library and a type checker such as mypy.

Upvotes: 1

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