Python nominal typing (with beartype)

test-int-subclass.py

from beartype import beartype

class MyInt(int):
    ...

def process_int_without(bar: int):
    print(f"process_int_without({bar} [type={type(bar)}])")

def process_myint_without(bar: MyInt):
    print(f"process_myint_without({bar} [type={type(bar)}])")

@beartype
def process_int_with(bar: int):
    print(f"process_int_with({bar} [type={type(bar)}])")

@beartype
def process_myint_with(bar: MyInt):
    print(f"process_myint_with({bar} [type={type(bar)}])")

foo_int: int = 5
foo_myint: MyInt = MyInt(6)

print("### Try both with int function")
process_int_without(foo_int)
process_int_without(foo_myint)

print("\n### Try both with MyInt function")
process_myint_without(foo_int)
process_myint_without(foo_myint)

print("\n### Try both with beartype int function")
process_int_with(foo_int)
process_int_with(foo_myint)

print("\n### Try both with beartype MyInt function")
try:
    process_myint_with(foo_int)
    print("no error?")
except Exception as e:
    print(f"process_myint_with({foo_int} [type={type(foo_int)}]) errored as expected: {e}")

process_myint_with(foo_myint)

print("\n### Starting tests with type-cast value")

foo_myint_to_int = int(foo_myint)
# Try both with beartype MyInt function
try:
    process_myint_with(foo_myint_to_int)
    print("no error?")
except Exception as e:
    print(f"process_myint_with({foo_int} [type={type(foo_int)}]) errored as expected: {e}")

process_myint_without(foo_myint_to_int)

$> python3 test-int-subclass.py
### Try both with int function
process_int_without(5 [type=<class 'int'>])
process_int_without(6 [type=<class '__main__.MyInt'>])

### Try both with MyInt function
process_myint_without(5 [type=<class 'int'>])
process_myint_without(6 [type=<class '__main__.MyInt'>])

### Try both with beartype int function
process_int_with(5 [type=<class 'int'>])
process_int_with(6 [type=<class '__main__.MyInt'>])

### Try both with beartype MyInt function
process_myint_with(5 [type=<class 'int'>]) errored as expected: Function __main__.process_myint_with() parameter bar=5 violates type hint <class '__main__.MyInt'>, as int 5 not instance of <protocol "__main__.MyInt">.
process_myint_with(6 [type=<class '__main__.MyInt'>])

### Starting tests with type-cast value
process_myint_with(5 [type=<class 'int'>]) errored as expected: Function __main__.process_myint_with() parameter bar=6 violates type hint <class '__main__.MyInt'>, as int 6 not instance of <protocol "__main__.MyInt">.
process_myint_without(6 [type=<class 'int'>])