pylock: use frozen dataclasses

Immutable objects are good.
In Python 3.9, it's a bit messy, though.

Author: sbidoul

src/pip/_internal/models/pylock.py

@@ -256,7 +256,7 @@ class PylockUnsupportedVersionError(PylockValidationError):
     pass
 
 
-@dataclass
+@dataclass(frozen=True)
 class PackageVcs:
     type: str
     url: Optional[str]  # = None
@@ -276,12 +276,12 @@ def __init__(
         subdirectory: Optional[str] = None,
     ) -> None:
         # In Python 3.10+ make dataclass kw_only=True and remove __init__
-        self.type = type
-        self.url = url
-        self.path = path
-        self.requested_revision = requested_revision
-        self.commit_id = commit_id
-        self.subdirectory = subdirectory
+        object.__setattr__(self, "type", type)
+        object.__setattr__(self, "url", url)
+        object.__setattr__(self, "path", path)
+        object.__setattr__(self, "requested_revision", requested_revision)
+        object.__setattr__(self, "commit_id", commit_id)
+        object.__setattr__(self, "subdirectory", subdirectory)
         # __post_init__ in Python 3.10+
         _validate_path_url(self.path, self.url)
 
@@ -297,7 +297,7 @@ def from_dict(cls, d: Dict[str, Any]) -> "Self":
         )
 
 
-@dataclass
+@dataclass(frozen=True)
 class PackageDirectory:
     path: str
     editable: Optional[bool] = None
@@ -311,9 +311,9 @@ def __init__(
         subdirectory: Optional[str] = None,
     ) -> None:
         # In Python 3.10+ make dataclass kw_only=True and remove __init__
-        self.path = path
-        self.editable = editable
-        self.subdirectory = subdirectory
+        object.__setattr__(self, "path", path)
+        object.__setattr__(self, "editable", editable)
+        object.__setattr__(self, "subdirectory", subdirectory)
 
     @classmethod
     def from_dict(cls, d: Dict[str, Any]) -> "Self":
@@ -324,7 +324,7 @@ def from_dict(cls, d: Dict[str, Any]) -> "Self":
         )
 
 
-@dataclass
+@dataclass(frozen=True)
 class PackageArchive:
     url: Optional[str]  # = None
     path: Optional[str]  # = None
@@ -344,12 +344,12 @@ def __init__(
         subdirectory: Optional[str] = None,
     ) -> None:
         # In Python 3.10+ make dataclass kw_only=True and remove __init__
-        self.url = url
-        self.path = path
-        self.size = size
-        self.upload_time = upload_time
-        self.hashes = hashes
-        self.subdirectory = subdirectory
+        object.__setattr__(self, "url", url)
+        object.__setattr__(self, "path", path)
+        object.__setattr__(self, "size", size)
+        object.__setattr__(self, "upload_time", upload_time)
+        object.__setattr__(self, "hashes", hashes)
+        object.__setattr__(self, "subdirectory", subdirectory)
         # __post_init__ in Python 3.10+
         _validate_path_url(self.path, self.url)
         _validate_hashes(self.hashes)
@@ -366,7 +366,7 @@ def from_dict(cls, d: Dict[str, Any]) -> "Self":
         )
 
 
-@dataclass
+@dataclass(frozen=True)
 class PackageSdist:
     name: str
     upload_time: Optional[datetime]  # = None
@@ -386,12 +386,12 @@ def __init__(
         size: Optional[int] = None,
     ) -> None:
         # In Python 3.10+ make dataclass kw_only=True and remove __init__
-        self.name = name
-        self.upload_time = upload_time
-        self.url = url
-        self.path = path
-        self.size = size
-        self.hashes = hashes
+        object.__setattr__(self, "name", name)
+        object.__setattr__(self, "upload_time", upload_time)
+        object.__setattr__(self, "url", url)
+        object.__setattr__(self, "path", path)
+        object.__setattr__(self, "size", size)
+        object.__setattr__(self, "hashes", hashes)
         # __post_init__ in Python 3.10+
         _validate_path_url(self.path, self.url)
         _validate_hashes(self.hashes)
@@ -408,7 +408,7 @@ def from_dict(cls, d: Dict[str, Any]) -> "Self":
         )
 
 
-@dataclass
+@dataclass(frozen=True)
 class PackageWheel:
     name: str
     upload_time: Optional[datetime]  # = None
@@ -428,12 +428,12 @@ def __init__(
         size: Optional[int] = None,
     ) -> None:
         # In Python 3.10+ make dataclass kw_only=True and remove __init__
-        self.name = name
-        self.upload_time = upload_time
-        self.url = url
-        self.path = path
-        self.size = size
-        self.hashes = hashes
+        object.__setattr__(self, "name", name)
+        object.__setattr__(self, "upload_time", upload_time)
+        object.__setattr__(self, "url", url)
+        object.__setattr__(self, "path", path)
+        object.__setattr__(self, "size", size)
+        object.__setattr__(self, "hashes", hashes)
         # __post_init__ in Python 3.10+
         _validate_path_url(self.path, self.url)
         _validate_hashes(self.hashes)
@@ -451,7 +451,7 @@ def from_dict(cls, d: Dict[str, Any]) -> "Self":
         return wheel
 
 
-@dataclass
+@dataclass(frozen=True)
 class Package:
     name: str
     version: Optional[Version] = None
@@ -485,19 +485,19 @@ def __init__(
         tool: Optional[Dict[str, Any]] = None,
     ) -> None:
         # In Python 3.10+ make dataclass kw_only=True and remove __init__
-        self.name = name
-        self.version = version
-        self.marker = marker
-        self.requires_python = requires_python
-        self.dependencies = dependencies
-        self.vcs = vcs
-        self.directory = directory
-        self.archive = archive
-        self.index = index
-        self.sdist = sdist
-        self.wheels = wheels
-        self.attestation_identities = attestation_identities
-        self.tool = tool
+        object.__setattr__(self, "name", name)
+        object.__setattr__(self, "version", version)
+        object.__setattr__(self, "marker", marker)
+        object.__setattr__(self, "requires_python", requires_python)
+        object.__setattr__(self, "dependencies", dependencies)
+        object.__setattr__(self, "vcs", vcs)
+        object.__setattr__(self, "directory", directory)
+        object.__setattr__(self, "archive", archive)
+        object.__setattr__(self, "index", index)
+        object.__setattr__(self, "sdist", sdist)
+        object.__setattr__(self, "wheels", wheels)
+        object.__setattr__(self, "attestation_identities", attestation_identities)
+        object.__setattr__(self, "tool", tool)
         # __post_init__ in Python 3.10+
         if self.sdist or self.wheels:
             if any([self.vcs, self.directory, self.archive]):
@@ -533,7 +533,7 @@ def from_dict(cls, d: Dict[str, Any]) -> "Self":
         return package
 
 
-@dataclass
+@dataclass(frozen=True)
 class Pylock:
     lock_version: Version
     environments: Optional[List[Marker]]  # = None
@@ -559,15 +559,15 @@ def __init__(
         tool: Optional[Dict[str, Any]] = None,
     ) -> None:
         # In Python 3.10+ make dataclass kw_only=True and remove __init__
-        self.lock_version = lock_version
-        self.environments = environments
-        self.requires_python = requires_python
-        self.extras = extras or []
-        self.dependency_groups = dependency_groups or []
-        self.default_groups = default_groups or []
-        self.created_by = created_by
-        self.packages = packages
-        self.tool = tool
+        object.__setattr__(self, "lock_version", lock_version)
+        object.__setattr__(self, "environments", environments)
+        object.__setattr__(self, "requires_python", requires_python)
+        object.__setattr__(self, "extras", extras or [])
+        object.__setattr__(self, "dependency_groups", dependency_groups or [])
+        object.__setattr__(self, "default_groups", default_groups or [])
+        object.__setattr__(self, "created_by", created_by)
+        object.__setattr__(self, "packages", packages)
+        object.__setattr__(self, "tool", tool)
         # __post_init__ in Python 3.10+
         if self.lock_version < Version("1") or self.lock_version >= Version("2"):
             raise PylockUnsupportedVersionError(