Runtime type checker

[k4ml]

Bumped into beartype and typeguard.

Python 3.10.8 (main, Nov  1 2022, 14:18:21) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> class MinF: pass
... 
>>> def get_insight(id: str) -> Minf:
...     return MinF()
... 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'Minf' is not defined. Did you mean: 'MinF'?
>>> def get_insight(id: str) -> MinF:
...     return MinF()
... 
>>> from beartype import beartype
>>> @beartype
... def get_insight(id: str) -> MinF:
...     return MinF()
... 
>>> get_insight(1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<@beartype(__main__.get_insight) at 0x7faac0ba24d0>", line 23, in get_insight
beartype.roar.BeartypeCallHintParamViolation: @beartyped __main__.get_insight() parameter id=1 violates type hint <class 'str'>, as int 1 not instance of str.
>>> minf: str = get_insight("hello")
>>> minf
<__main__.MinF object at 0x7faac0d0b520>
>>> @beartype
... def get_insight(id: str) -> MinF:
...     return "hello"
... 
>>> minf: str = get_insight("hello")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<@beartype(__main__.get_insight) at 0x7faac0ba2440>", line 40, in get_insight
beartype.roar.BeartypeCallHintReturnViolation: @beartyped __main__.get_insight() return 'hello' violates type hint <class '__main__.MinF'>, as str 'hello' not instance of <class "__main__.MinF">.
>>> minf: str = get_insight("hello")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<@beartype(__main__.get_insight) at 0x7faac0ba2440>", line 40, in get_insight
beartype.roar.BeartypeCallHintReturnViolation: @beartyped __main__.get_insight() return 'hello' violates type hint <class '__main__.MinF'>, as str 'hello' not instance of <class "__main__.MinF">.
>>> @beartype
... def get_insight(id: str) -> MinF:
...     return MinF()
... 
>>> minf: str = get_insight("hello")
>>> minf
<__main__.MinF object at 0x7faac08afc70>
>>> from beartype.vale import Is
>>> minf: str = Is[get_insight("hello"), MinF]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/kamal-kde/python/venv/lib/python3.10/site-packages/beartype/vale/_is/_valeis.py", line 334, in __getitem__
    self._die_unless_getitem_args_1(is_valid)
  File "/home/kamal-kde/python/venv/lib/python3.10/site-packages/beartype/vale/_is/_valeisabc.py", line 144, in _die_unless_getitem_args_1
    raise BeartypeValeSubscriptionException(
beartype.roar.BeartypeValeSubscriptionException: Beartype validator factory "Is" subscripted by two or more arguments (<__main__.MinF object at 0x7faac0a43760>, <class '__main__.MinF'>).
>>> minf: str = Is[get_insight("hello")==MinF]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/kamal-kde/python/venv/lib/python3.10/site-packages/beartype/vale/_is/_valeis.py", line 338, in __getitem__
    die_unless_validator_tester(is_valid)
  File "/home/kamal-kde/python/venv/lib/python3.10/site-packages/beartype/vale/_util/_valeutilfunc.py", line 46, in die_unless_validator_tester
    die_unless_func_args_len_flexible_equal(
  File "/home/kamal-kde/python/venv/lib/python3.10/site-packages/beartype/_util/func/arg/utilfuncargtest.py", line 81, in die_unless_func_args_len_flexible_equal
    func_args_len_flexible_actual = get_func_args_len_flexible(
  File "/home/kamal-kde/python/venv/lib/python3.10/site-packages/beartype/_util/func/arg/utilfuncargget.py", line 78, in get_func_args_len_flexible
    func_codeobj = get_func_codeobj(func=func, exception_cls=exception_cls)
  File "/home/kamal-kde/python/venv/lib/python3.10/site-packages/beartype/_util/func/utilfunccodeobj.py", line 125, in get_func_codeobj
    die_unless_func_python(func=func, exception_cls=exception_cls)
  File "/home/kamal-kde/python/venv/lib/python3.10/site-packages/beartype/_util/func/utilfunctest.py", line 101, in die_unless_func_python
    raise exception_cls(f'{exception_prefix}{repr(func)} not callable.')
beartype.roar.BeartypeValeSubscriptionException: False not callable.
>>> from beartype.door import die_if_unbearable
>>> minf: str = get_insight("hello")
>>> str
<class 'str'>
>>> minf
<__main__.MinF object at 0x7faac0901ae0>
>>> die_if_unbearable(minf)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: die_if_unbearable() missing 1 required positional argument: 'hint'
>>> die_if_unbearable(minf, MinF)
>>> die_if_unbearable(minf, str)
Traceback (most recent call last):
  File "/home/kamal-kde/python/venv/lib/python3.10/site-packages/beartype/door/_doorcheck.py", line 147, in die_if_unbearable
    _check_object(obj)
  File "<@beartype(beartype.door._doorcheck._get_type_checker._die_if_unbearable) at 0x7faac095cee0>", line 18, in _die_if_unbearable
beartype.roar.BeartypeCallHintReturnViolation: @beartyped beartype.door._doorcheck._get_type_checker._die_if_unbearable() return <__main__.MinF object at 0x7faac0901ae0> violates type hint <class 'str'>, as <class "__main__.MinF"> <__main__.MinF object at 0x7faac0901ae0> not instance of str.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/kamal-kde/python/venv/lib/python3.10/site-packages/beartype/door/_doorcheck.py", line 177, in die_if_unbearable
    raise BeartypeDoorHintViolation(
beartype.roar.BeartypeDoorHintViolation: Object <__main__.MinF object at 0x7faac0901ae0> violates type hint <class 'str'>, as <class "__main__.MinF"> <__main__.MinF object at 0x7faac0901ae0> not instance of str

[k4ml]

What I want is something that can type check an assignment:-

minf: Minf = get_insight("hello")

beartype only doing check on the call to get_insight() (since we decorated it with @beartype) but not on the assignment. Even we put type hint that minf should be of type MinF, nothing stopping as from assigning a str to it.

[k4ml]

Typeguard has modules instrumentation so we can tell it to type check the whole modules with having to decorate individual functions/class.