CODEWITHSUNDEEP
pythontype-hinting
Aethalides
Aethalides

Reputation: 407

how do I enforce this type checking? The code allows any type to be returned or passed

I'm trying to use type hints. My tests so far allow defining type hints but they do not seem to be enforced.

from typing import Type,TypeVar

MyType=TypeVar("MyType",bound="my")

class my:
    @staticmethod
    def factory(test) -> MyType:
        if test==1:
                return my(1)
        if test==2:
                return Exception("what am I")
        return None
    def __init__(self,thevar):
        self.test=thevar
    def typecheck(var: MyType):
        print("function called with type %s" % type(var))

myclass=my("")
for test in range(0,3):
    thevar=my.factory(test)
    print ("My type is %s" % type(thevar))
    my.typecheck(thevar)

I am expecting errors to be raised when the wrong type is passed or returned. Except perhaps for when a None is returned instead of a class

Upvotes: 2

Views: 1200

Answers (1)

Evan
Evan

Reputation: 2301

As Aaron mentioned, this is usually done with another tool (mypy), rather than the python interpreter.

To install mypy (from the docs):

$ python3 -m pip install mypy

Then, to type check your code with mypy:

$ mypy program.py

Upvotes: 4

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