feature: API checks: Check for types compatibility about griffe HOT 3 OPEN

Moving this here from the README:

• List of things to consider for breaking changes
  • Changed type of parameter
  • Changed type of public module attribute
  • Changed return type of a public function/method
  • All of the previous even when parent is private (could be publicly imported or assigned somewhere),
    and later be smarter: public assign/import makes private things public!
  • Inheritance: removed, added or changed base that changes MRO

from griffe.

I wonder: could we somehow recurse into objects to check that they implement the same "protocols"? Example:

class Foo:
    def method1(self): ...
    def method2(self, param1: int, param2: int): ...

class Bar:
    def method2(self, param1: int, param2: int): ...

class Baz:
    def method1(self): ...
    def method2(self, param1: int): ...

class Qux:
    def method1(self): ...
    def method2(self, param1: str, param2: int): ...

class Quux:
    def method1(self): ...
    def method2(self, param1: int, param2: int): ...
    def method3(self): ...

def f_old(param: Foo): ...

def f_new(param: Bar): ...  # breaks: removed method1
def f_new(param: Baz): ...  # breaks: removed param2 on method2
def f_new(param: Qux): ...  # breaks: changed type of param1 on method2 (int -> str is a "known" breakage)
def f_new(param: Quux): ...  # doesn't break: added method3

I imagine a type_compatible(self, other) method on objects that uses next(find_breaking_changes(self, other)) and returns False if a breakage is yielded, True if StopIteration is raised.

from griffe.

Or maybe there's a way to hook into mypy...

from griffe.