Closes #228

Author: sobolevn

CHANGELOG.md

@@ -9,6 +9,8 @@ We follow Semantic Versions since the `0.1.0` release.
 
 - **Breaking**: drops `python3.6` support
 - **Breaking**: now requires `typing_extensions>=3.10` and `mypy>=0.902`
+- **Breaking**: now `classes` traverses `mro` of registered types
+  and fallbacks to super-types if some type is not registered
 - Adds generic typeclasses
 - Adds better typeclass validation during `mypy` typechecking
 - Adds `.supports()` method to typeclass to check

classes/contrib/mypy/validation/validate_runtime.py

@@ -34,6 +34,10 @@
     'Runtime type "{0}" has unbound type, use implicit any'
 )
 
+_TUPLE_LENGTH_MSG: Final = (
+    'Expected variadic tuple "Tuple[{0}, ...]", got "{1}"'
+)
+
 
 class _RuntimeValidationContext(NamedTuple):
     runtime_type: MypyType
@@ -85,7 +89,8 @@ def check_instance_definition(
 
     return _RuntimeValidationContext(runtime_type, is_protocol, all([
         _check_runtime_protocol(runtime_type, ctx, is_protocol=is_protocol),
-        _check_concrete_generics(instance_type, runtime_type, ctx),
+        _check_concrete_generics(runtime_type, instance_type, ctx),
+        _check_tuple_size(instance_type, ctx),
         protocol_arg_check,
         instance_check,
     ]))
@@ -128,8 +133,8 @@ def _check_runtime_protocol(
 
 
 def _check_concrete_generics(
-    instance_type: MypyType,
     runtime_type: MypyType,
+    instance_type: MypyType,
     ctx: MethodContext,
 ) -> bool:
     has_concrete_type = False
@@ -152,3 +157,16 @@ def _check_concrete_generics(
         ctx.api.fail(_UNBOUND_TYPE_MSG.format(runtime_type), ctx.context)
         return False
     return not has_concrete_type
+
+
+def _check_tuple_size(
+    instance_type: MypyType,
+    ctx: MethodContext,
+) -> bool:
+    if isinstance(instance_type, TupleType):
+        ctx.api.fail(
+            _TUPLE_LENGTH_MSG.format(instance_type.items[0], instance_type),
+            ctx.context,
+        )
+        return False
+    return True

typesafety/test_typeclass/test_generics/test_generics_regular.yml

@@ -253,3 +253,22 @@
   out: |
     main:9: error: Generic type "main.Copy" with "0" type arguments does not match generic instance declaration "typing.Iterable[X`-1]" with "1" type arguments
     main:23: note: Revealed type is "<nothing>"
+
+
+- case: typeclass_generic_tuple
+  disable_cache: false
+  main: |
+    from typing import Iterable, Tuple, TypeVar
+    from classes import typeclass
+
+    X = TypeVar('X')
+
+    @typeclass
+    def some(instance: Iterable[X]) -> X:
+        ...
+
+    @some.instance(tuple)
+    def _some_tuple(instance: Tuple[X, X]) -> X:
+        ...
+  out: |
+    main:10: error: Expected variadic tuple "Tuple[X`-1, ...]", got "Tuple[X`-1, X`-1]"