Update stdblib/shelve.pyi (#5816)

Several things done:

1. Replace all occurrences of `Any` by respective concrete types.
2. Make `Shelf` and its subclassses generic. (Fixes #5815)
3. `shelve.open` should return a general `Shelf` object, not `DbfilenameShelf`. The documentation does not expose such implementation detail.
4. The argument `dict` is annotated with an abstract type `MutableMapping` rather than concrete type `Dict`.
5. Remove unnecessary methods. Some of them are inherited from `MutableMapping`, so no need to repeat them here.
6. Use builtin-in generics instead of importing from `typing`.

stdlib/shelve.pyi

@@ -1,35 +1,39 @@
-import collections.abc
 from _typeshed import Self
-from typing import Any, Dict, Iterator, Optional, Tuple
+from collections.abc import Iterator, MutableMapping
+from types import TracebackType
+from typing import Optional, Type, TypeVar, Union, overload
 
-class Shelf(collections.abc.MutableMapping[Any, Any]):
+_T = TypeVar("_T")
+_VT = TypeVar("_VT")
+
+class Shelf(MutableMapping[str, _VT]):
     def __init__(
-        self, dict: Dict[bytes, Any], protocol: Optional[int] = ..., writeback: bool = ..., keyencoding: str = ...
+        self, dict: MutableMapping[bytes, bytes], protocol: Optional[int] = ..., writeback: bool = ..., keyencoding: str = ...
     ) -> None: ...
     def __iter__(self) -> Iterator[str]: ...
     def __len__(self) -> int: ...
-    def __contains__(self, key: Any) -> bool: ...  # key should be str, but it would conflict with superclass's type signature
-    def get(self, key: str, default: Any = ...) -> Any: ...
-    def __getitem__(self, key: str) -> Any: ...
-    def __setitem__(self, key: str, value: Any) -> None: ...
+    @overload
+    def get(self, key: str) -> Optional[_VT]: ...
+    @overload
+    def get(self, key: str, default: _T) -> Union[_VT, _T]: ...
+    def __getitem__(self, key: str) -> _VT: ...
+    def __setitem__(self, key: str, value: _VT) -> None: ...
     def __delitem__(self, key: str) -> None: ...
     def __enter__(self: Self) -> Self: ...
-    def __exit__(self, type: Any, value: Any, traceback: Any) -> None: ...
+    def __exit__(
+        self, type: Optional[Type[BaseException]], value: Optional[BaseException], traceback: Optional[TracebackType]
+    ) -> None: ...
     def close(self) -> None: ...
-    def __del__(self) -> None: ...
     def sync(self) -> None: ...
 
-class BsdDbShelf(Shelf):
-    def __init__(
-        self, dict: Dict[bytes, Any], protocol: Optional[int] = ..., writeback: bool = ..., keyencoding: str = ...
-    ) -> None: ...
-    def set_location(self, key: Any) -> Tuple[str, Any]: ...
-    def next(self) -> Tuple[str, Any]: ...
-    def previous(self) -> Tuple[str, Any]: ...
-    def first(self) -> Tuple[str, Any]: ...
-    def last(self) -> Tuple[str, Any]: ...
+class BsdDbShelf(Shelf[_VT]):
+    def set_location(self, key: str) -> tuple[str, _VT]: ...
+    def next(self) -> tuple[str, _VT]: ...
+    def previous(self) -> tuple[str, _VT]: ...
+    def first(self) -> tuple[str, _VT]: ...
+    def last(self) -> tuple[str, _VT]: ...
 
-class DbfilenameShelf(Shelf):
+class DbfilenameShelf(Shelf[_VT]):
     def __init__(self, filename: str, flag: str = ..., protocol: Optional[int] = ..., writeback: bool = ...) -> None: ...
 
-def open(filename: str, flag: str = ..., protocol: Optional[int] = ..., writeback: bool = ...) -> DbfilenameShelf: ...
+def open(filename: str, flag: str = ..., protocol: Optional[int] = ..., writeback: bool = ...) -> Shelf[object]: ...