Use attrs.define instead of dataclasses

- Split the changelog
- Use TypeGuard correctly
- Remove `transform` in favor of `__attrs_post_init__` to allow for a more personalized use of `validate`
- Remove `define` from the docs, change format in changelog

Author: LiteApplication

changes/285.internal.1.md

@@ -0,0 +1,57 @@
+- Changed the way `Serializable` classes are handled:
+
+  Here is how a basic `Serializable` class looks like:
+
+  ```python
+    @final
+    @dataclass
+    class ToyClass(Serializable):
+        """Toy class for testing demonstrating the use of gen_serializable_test on `Serializable`."""
+
+        a: int
+        b: str | int
+
+        @override
+        def __attrs_post_init__(self):
+            """Initialize the object."""
+            if isinstance(self.b, int):
+                self.b = str(self.b)
+
+            super().__attrs_post_init__() # This will call validate()
+
+        @override
+        def serialize_to(self, buf: Buffer):
+            """Write the object to a buffer."""
+            self.b = cast(str, self.b)  # Handled by the __attrs_post_init__ method
+            buf.write_varint(self.a)
+            buf.write_utf(self.b)
+
+        @classmethod
+        @override
+        def deserialize(cls, buf: Buffer) -> ToyClass:
+            """Deserialize the object from a buffer."""
+            a = buf.read_varint()
+            if a == 0:
+                raise ZeroDivisionError("a must be non-zero")
+            b = buf.read_utf()
+            return cls(a, b)
+
+        @override
+        def validate(self) -> None:
+            """Validate the object's attributes."""
+            if self.a == 0:
+                raise ZeroDivisionError("a must be non-zero")
+            if len(self.b) > 10:
+                raise ValueError("b must be less than 10 characters")
+
+  ```
+
+The `Serializable` class implement the following methods:
+
+  - `serialize_to(buf: Buffer) -> None`: Serializes the object to a buffer.
+  - `deserialize(buf: Buffer) -> Serializable`: Deserializes the object from a buffer.
+
+  And the following optional methods:
+
+  - `validate() -> None`: Validates the object's attributes, raising an exception if they are invalid.
+  - `__attrs_post_init__() -> None`: Initializes the object. Call `super().__attrs_post_init__()` to validate the object.

changes/285.internal.md renamed to changes/285.internal.2.md

@@ -1,57 +1,3 @@
-- Changed the way `Serializable` classes are handled:
-
-Here is how a basic `Serializable` class looks like:
-```python
-    @final
-    @dataclass
-    class ToyClass(Serializable):
-        """Toy class for testing demonstrating the use of gen_serializable_test on `Serializable`."""
-
-        a: int
-        b: str | int
-
-        @override
-        def serialize_to(self, buf: Buffer):
-            """Write the object to a buffer."""
-            self.b = cast(str, self.b)  # Handled by the transform method
-            buf.write_varint(self.a)
-            buf.write_utf(self.b)
-
-        @classmethod
-        @override
-        def deserialize(cls, buf: Buffer) -> ToyClass:
-            """Deserialize the object from a buffer."""
-            a = buf.read_varint()
-            if a == 0:
-                raise ZeroDivisionError("a must be non-zero")
-            b = buf.read_utf()
-            return cls(a, b)
-
-        @override
-        def validate(self) -> None:
-            """Validate the object's attributes."""
-            if self.a == 0:
-                raise ZeroDivisionError("a must be non-zero")
-            if (isinstance(self.b, int) and math.log10(self.b) > 10) or (isinstance(self.b, str) and len(self.b) > 10):
-                raise ValueError("b must be less than 10 characters")
-
-        @override
-        def transform(self) -> None:
-            """Apply a transformation to the payload of the object."""
-            if isinstance(self.b, int):
-                self.b = str(self.b)
-```
-
-
-The `Serializable` class implement the following methods:
-- `serialize_to(buf: Buffer) -> None`: Serializes the object to a buffer.
-- `deserialize(buf: Buffer) -> Serializable`: Deserializes the object from a buffer.
-
-And the following optional methods:
-  - `validate() -> None`: Validates the object's attributes, raising an exception if they are invalid.
-  - `transform() -> None`: Transforms the the object's attributes, this method is meant to convert types like you would in a classic `__init__`.
-  You can rely on this `validate` having been executed.
-
 - Added a test generator for `Serializable` classes:
 
   The `gen_serializable_test` function generates tests for `Serializable` classes. It takes the following arguments:
@@ -69,6 +15,7 @@ And the following optional methods:
     - `(exception, bytes)`: The expected exception when deserializing the bytes and the bytes to deserialize.
 
   The `gen_serializable_test` function generates a test class with the following tests:
+
 ```python
 gen_serializable_test(
     context=globals(),
@@ -80,7 +27,7 @@ gen_serializable_test(
         ((3, 1234567890), b"\x03\x0a1234567890"),
         ((0, "hello"), ZeroDivisionError("a must be non-zero")), # With an error message
         ((1, "hello world"), ValueError), # No error message
-        ((1, 12345678900), ValueError),
+        ((1, 12345678900), ValueError("b must be less than 10 .*")), # With an error message and regex
         (ZeroDivisionError, b"\x00"),
         (ZeroDivisionError, b"\x01\x05hello"),
         (IOError, b"\x01"),
@@ -90,7 +37,7 @@ gen_serializable_test(
 
   The generated test class will have the following tests:
 
-```python
+  ```python
 class TestGenToyClass:
     def test_serialization(self):
         # 2 subtests for the cases 1 and 2
@@ -103,4 +50,4 @@ class TestGenToyClass:
 
     def test_exceptions(self):
         # 2 subtests for the cases 5 and 6
-```
+  ```

docs/api/internal.rst

@@ -7,6 +7,7 @@ should not be used externally**, as we do not guarantee their backwards compatib
 may be introduced between patch versions without any warnings.
 
 .. automodule:: mcproto.utils.abc
+    :exclude-members: define
 
 .. autofunction:: tests.helpers.gen_serializable_test
 ..

mcproto/packets/handshaking/handshake.py

@@ -8,7 +8,7 @@
 from mcproto.buffer import Buffer
 from mcproto.packets.packet import GameState, ServerBoundPacket
 from mcproto.protocol.base_io import StructFormat
-from mcproto.utils.abc import dataclass
+from mcproto.utils.abc import define
 
 __all__ = [
     "NextState",
@@ -24,7 +24,7 @@ class NextState(IntEnum):
 
 
 @final
-@dataclass
+@define
 class Handshake(ServerBoundPacket):
     """Initializes connection between server and client. (Client -> Server).
 
@@ -44,10 +44,17 @@ class Handshake(ServerBoundPacket):
     server_port: int
     next_state: NextState | int
 
+    @override
+    def __attrs_post_init__(self) -> None:
+        if not isinstance(self.next_state, NextState):
+            self.next_state = NextState(self.next_state)
+
+        super().__attrs_post_init__()
+
     @override
     def serialize_to(self, buf: Buffer) -> None:
         """Serialize the packet."""
-        self.next_state = cast(NextState, self.next_state)  # Handled by the transform method
+        self.next_state = cast(NextState, self.next_state)  # Handled by the __attrs_post_init__ method
         buf.write_varint(self.protocol_version)
         buf.write_utf(self.server_address)
         buf.write_value(StructFormat.USHORT, self.server_port)
@@ -69,8 +76,3 @@ def validate(self) -> None:
             rev_lookup = {x.value: x for x in NextState.__members__.values()}
             if self.next_state not in rev_lookup:
                 raise ValueError("No such next_state.")
-
-    @override
-    def transform(self) -> None:
-        """Get the next state enum from the integer value."""
-        self.next_state = NextState(self.next_state)

mcproto/packets/login/login.py

@@ -11,7 +11,7 @@
 from mcproto.packets.packet import ClientBoundPacket, GameState, ServerBoundPacket
 from mcproto.types.chat import ChatMessage
 from mcproto.types.uuid import UUID
-from mcproto.utils.abc import dataclass
+from mcproto.utils.abc import define
 
 __all__ = [
     "LoginDisconnect",
@@ -26,7 +26,7 @@
 
 
 @final
-@dataclass
+@define
 class LoginStart(ServerBoundPacket):
     """Packet from client asking to start login process. (Client -> Server).
 
@@ -56,7 +56,7 @@ def _deserialize(cls, buf: Buffer, /) -> Self:
 
 
 @final
-@dataclass
+@define
 class LoginEncryptionRequest(ClientBoundPacket):
     """Used by the server to ask the client to encrypt the login process. (Server -> Client).
 
@@ -74,6 +74,13 @@ class LoginEncryptionRequest(ClientBoundPacket):
     verify_token: bytes
     server_id: str | None = None
 
+    @override
+    def __attrs_post_init__(self) -> None:
+        if self.server_id is None:
+            self.server_id = " " * 20
+
+        super().__attrs_post_init__()
+
     @override
     def serialize_to(self, buf: Buffer) -> None:
         self.server_id = cast(str, self.server_id)
@@ -96,14 +103,9 @@ def _deserialize(cls, buf: Buffer, /) -> Self:
 
         return cls(server_id=server_id, public_key=public_key, verify_token=verify_token)
 
-    @override
-    def transform(self) -> None:
-        if self.server_id is None:
-            self.server_id = " " * 20
-
 
 @final
-@dataclass
+@define
 class LoginEncryptionResponse(ServerBoundPacket):
     """Response from the client to :class:`LoginEncryptionRequest` packet. (Client -> Server).
 
@@ -134,7 +136,7 @@ def _deserialize(cls, buf: Buffer, /) -> Self:
 
 
 @final
-@dataclass
+@define
 class LoginSuccess(ClientBoundPacket):
     """Sent by the server to denote a successful login. (Server -> Client).
 
@@ -164,7 +166,7 @@ def _deserialize(cls, buf: Buffer, /) -> Self:
 
 
 @final
-@dataclass
+@define
 class LoginDisconnect(ClientBoundPacket):
     """Sent by the server to kick a player while in the login state. (Server -> Client).
 
@@ -190,7 +192,7 @@ def _deserialize(cls, buf: Buffer, /) -> Self:
 
 
 @final
-@dataclass
+@define
 class LoginPluginRequest(ClientBoundPacket):
     """Sent by the server to implement a custom handshaking flow. (Server -> Client).
 
@@ -224,7 +226,7 @@ def _deserialize(cls, buf: Buffer, /) -> Self:
 
 
 @final
-@dataclass
+@define
 class LoginPluginResponse(ServerBoundPacket):
     """Response to LoginPluginRequest from client. (Client -> Server).
 
@@ -254,7 +256,7 @@ def _deserialize(cls, buf: Buffer, /) -> Self:
 
 
 @final
-@dataclass
+@define
 class LoginSetCompression(ClientBoundPacket):
     """Sent by the server to specify whether to use compression on future packets or not (Server -> Client).
 

mcproto/packets/status/ping.py

@@ -7,13 +7,13 @@
 from mcproto.buffer import Buffer
 from mcproto.packets.packet import ClientBoundPacket, GameState, ServerBoundPacket
 from mcproto.protocol.base_io import StructFormat
-from mcproto.utils.abc import dataclass
+from mcproto.utils.abc import define
 
 __all__ = ["PingPong"]
 
 
 @final
-@dataclass
+@define
 class PingPong(ClientBoundPacket, ServerBoundPacket):
     """Ping request/Pong response (Server <-> Client).
 

mcproto/packets/status/status.py

@@ -7,13 +7,13 @@
 
 from mcproto.buffer import Buffer
 from mcproto.packets.packet import ClientBoundPacket, GameState, ServerBoundPacket
-from mcproto.utils.abc import dataclass
+from mcproto.utils.abc import define
 
 __all__ = ["StatusRequest", "StatusResponse"]
 
 
 @final
-@dataclass
+@define
 class StatusRequest(ServerBoundPacket):
     """Request from the client to get information on the server. (Client -> Server)."""
 
@@ -31,7 +31,7 @@ def _deserialize(cls, buf: Buffer, /) -> Self:  # pragma: no cover, nothing to t
 
 
 @final
-@dataclass
+@define
 class StatusResponse(ClientBoundPacket):
     """Response from the server to requesting client with status data information. (Server -> Client).
 

mcproto/types/abc.py

@@ -1,8 +1,8 @@
 from __future__ import annotations
 
-from mcproto.utils.abc import Serializable, dataclass
+from mcproto.utils.abc import Serializable, define
 
-__all__ = ["MCType", "dataclass"]  # That way we can import it from mcproto.types.abc
+__all__ = ["MCType", "define"]  # That way we can import it from mcproto.types.abc
 
 
 class MCType(Serializable):

mcproto/types/chat.py

@@ -6,7 +6,7 @@
 from typing_extensions import Self, TypeAlias, override
 
 from mcproto.buffer import Buffer
-from mcproto.types.abc import MCType, dataclass
+from mcproto.types.abc import MCType, define
 
 __all__ = [
     "ChatMessage",
@@ -33,13 +33,15 @@ class RawChatMessageDict(TypedDict, total=False):
 RawChatMessage: TypeAlias = Union[RawChatMessageDict, "list[RawChatMessageDict]", str]
 
 
-@dataclass
 @final
+@define
 class ChatMessage(MCType):
     """Minecraft chat message representation."""
 
     raw: RawChatMessage
 
+    __slots__ = ("raw",)
+
     def as_dict(self) -> RawChatMessageDict:
         """Convert received ``raw`` into a stadard :class:`dict` form."""
         if isinstance(self.raw, list):