Open
Description
Feature or enhancement
hashlib describes a Protocol for hash objects without implementing it.
The proposal is simply to create a concreate Hash or HashObject protocol that makes it explicit.
Pitch
Using the Buffer Protocol (PEP 688) this should look something like
@runtime_checkable
class Hash(Protocol):
name: str
def digest_size(self) -> int:
"""Return the size of the hash in bytes."""
def block_size(self) -> int:
"""Return the internal block size of the hash in bytes."""
def update(self, data: Buffer) -> None:
"""Update this hash object's state with the provided string."""
def digest(self) -> bytes:
"""Return the digest value as a string of binary data."""
def hexdigest(self) -> str:
"""Return the digest value as a string of hexadecimal digits."""
def copy(self) -> Self:
"""Return a copy ("clone") of the hash object."""Having a Protocol class instead of prose makes it clear how exactly a hash-function needs to look like.
A second suggestion would be to change hashlib.algorithms_guaranteed and hashlib.algorithms_available from set[str] to dict[str, type[Hash]] objects.