Start phasing out frozen_after_init (pantsbuild#18047)

As discussed on Slack, `frozen_after_init` has a few drawbacks:

- We lose the normal "frozen" benefits from dataclass
- You have to remember to use `unsafe_hash`, because...
- Type checkers won't help you identify when assign a variable. You're on your own
- These are mostly used for converters. If/when those get into stdlib `dataclass` we could eliminate a lot of this code.

On the other hand, the standard library already spells out what to do in this situation: https://docs.python.org/3/library/dataclasses.html#frozen-instances. I love doing as the Romans do 😉 

After we switch internally, we can deprecate the function for a few releases

pants-plugins/internal_plugins/test_lockfile_fixtures/lockfile_fixture.py

@@ -13,22 +13,16 @@
 from pants.jvm.resolve.coursier_fetch import CoursierResolvedLockfile
 from pants.jvm.resolve.lockfile_metadata import LockfileContext
 from pants.util.docutil import bin_name
-from pants.util.meta import frozen_after_init
 
 
-@frozen_after_init
-@dataclass(unsafe_hash=True)
+@dataclass(frozen=True)
 class JVMLockfileFixtureDefinition:
     lockfile_rel_path: Path
     requirements: tuple[Coordinate, ...]
 
     def __init__(
         self, lockfile_rel_path: Path | str, requirements: Iterable[Coordinate | str]
     ) -> None:
-        self.lockfile_rel_path = (
-            lockfile_rel_path if isinstance(lockfile_rel_path, Path) else Path(lockfile_rel_path)
-        )
-
         coordinates: list[Coordinate] = []
         for requirement in requirements:
             if isinstance(requirement, Coordinate):
@@ -40,7 +34,13 @@ def __init__(
                 raise TypeError(
                     f"Unsupported type `{type(requirement)}` for JVM coordinate. Expected `Coordinate` or `str`."
                 )
-        self.requirements = tuple(coordinates)
+
+        object.__setattr__(
+            self,
+            "lockfile_rel_path",
+            lockfile_rel_path if isinstance(lockfile_rel_path, Path) else Path(lockfile_rel_path),
+        )
+        object.__setattr__(self, "requirements", tuple(coordinates))
 
     @classmethod
     def from_json_dict(cls, kwargs) -> JVMLockfileFixtureDefinition:

src/python/pants/BUILD

@@ -11,6 +11,7 @@ python_sources(
 )
 
 python_test_utils(name="test_utils")
+python_tests(name="tests")
 
 python_distribution(
     name="pants-packaged",

src/python/pants/backend/go/util_rules/embedcfg.py

@@ -8,12 +8,10 @@
 from typing import Any, Iterable, Mapping
 
 from pants.util.frozendict import FrozenDict
-from pants.util.meta import frozen_after_init
 from pants.util.strutil import strip_prefix
 
 
-@dataclass(unsafe_hash=True)
-@frozen_after_init
+@dataclass(frozen=True)
 class EmbedConfig:
     patterns: FrozenDict[str, tuple[str, ...]]
     files: FrozenDict[str, str]
@@ -35,8 +33,8 @@ def __init__(self, patterns: Mapping[str, Iterable[str]], files: Mapping[str, st
         :param files: Maps each virtual, relative file path used as a value in the `patterns`
           dictionary to the actual filesystem path with that file's content.
         """
-        self.patterns = FrozenDict({k: tuple(v) for k, v in patterns.items()})
-        self.files = FrozenDict(files)
+        object.__setattr__(self, "patterns", FrozenDict({k: tuple(v) for k, v in patterns.items()}))
+        object.__setattr__(self, "files", FrozenDict(files))
 
     @classmethod
     def from_json_dict(

src/python/pants/backend/go/util_rules/sdk.py

@@ -18,11 +18,9 @@
 from pants.engine.rules import collect_rules, rule
 from pants.util.frozendict import FrozenDict
 from pants.util.logging import LogLevel
-from pants.util.meta import frozen_after_init
 
 
-@frozen_after_init
-@dataclass(unsafe_hash=True)
+@dataclass(frozen=True)
 class GoSdkProcess:
     command: tuple[str, ...]
     description: str
@@ -46,18 +44,22 @@ def __init__(
         allow_downloads: bool = False,
         replace_sandbox_root_in_args: bool = False,
     ) -> None:
-        self.command = tuple(command)
-        self.description = description
-        self.env = (
-            FrozenDict(env or {})
-            if allow_downloads
-            else FrozenDict({**(env or {}), "GOPROXY": "off"})
+        object.__setattr__(self, "command", tuple(command))
+        object.__setattr__(self, "description", description)
+        object.__setattr__(
+            self,
+            "env",
+            (
+                FrozenDict(env or {})
+                if allow_downloads
+                else FrozenDict({**(env or {}), "GOPROXY": "off"})
+            ),
         )
-        self.input_digest = input_digest
-        self.working_dir = working_dir
-        self.output_files = tuple(output_files)
-        self.output_directories = tuple(output_directories)
-        self.replace_sandbox_root_in_args = replace_sandbox_root_in_args
+        object.__setattr__(self, "input_digest", input_digest)
+        object.__setattr__(self, "working_dir", working_dir)
+        object.__setattr__(self, "output_files", tuple(output_files))
+        object.__setattr__(self, "output_directories", tuple(output_directories))
+        object.__setattr__(self, "replace_sandbox_root_in_args", replace_sandbox_root_in_args)
 
 
 @dataclass(frozen=True)

src/python/pants/backend/helm/subsystems/post_renderer.py

@@ -36,7 +36,6 @@
 from pants.util.docutil import git_url
 from pants.util.frozendict import FrozenDict
 from pants.util.logging import LogLevel
-from pants.util.meta import frozen_after_init
 from pants.util.strutil import bullet_list, pluralize, softwrap
 
 logger = logging.getLogger(__name__)
@@ -126,8 +125,7 @@ def debug_hint(self) -> str | None:
         return self.description_of_origin
 
 
-@frozen_after_init
-@dataclass(unsafe_hash=True)
+@dataclass(frozen=True)
 class HelmPostRenderer(EngineAwareReturnType):
     exe: str
     digest: Digest
@@ -146,12 +144,14 @@ def __init__(
         immutable_input_digests: Mapping[str, Digest] | None = None,
         append_only_caches: Mapping[str, str] | None = None,
     ) -> None:
-        self.exe = exe
-        self.digest = digest
-        self.description_of_origin = description_of_origin
-        self.env = FrozenDict(env or {})
-        self.append_only_caches = FrozenDict(append_only_caches or {})
-        self.immutable_input_digests = FrozenDict(immutable_input_digests or {})
+        object.__setattr__(self, "exe", exe)
+        object.__setattr__(self, "digest", digest)
+        object.__setattr__(self, "description_of_origin", description_of_origin)
+        object.__setattr__(self, "env", FrozenDict(env or {}))
+        object.__setattr__(self, "append_only_caches", FrozenDict(append_only_caches or {}))
+        object.__setattr__(
+            self, "immutable_input_digests", FrozenDict(immutable_input_digests or {})
+        )
 
     def level(self) -> LogLevel | None:
         return LogLevel.DEBUG

src/python/pants/backend/helm/util_rules/renderer.py

@@ -42,7 +42,6 @@
 from pants.engine.process import InteractiveProcess, Process, ProcessCacheScope, ProcessResult
 from pants.engine.rules import Get, MultiGet, collect_rules, rule, rule_helper
 from pants.util.logging import LogLevel
-from pants.util.meta import frozen_after_init
 from pants.util.strutil import pluralize, softwrap
 from pants.util.value_interpolation import InterpolationContext, InterpolationValue
 
@@ -56,8 +55,7 @@ class HelmDeploymentCmd(Enum):
     RENDER = "template"
 
 
-@dataclass(unsafe_hash=True)
-@frozen_after_init
+@dataclass(frozen=True)
 class HelmDeploymentRequest(EngineAwareParameter):
     field_set: HelmDeploymentFieldSet
 
@@ -75,11 +73,11 @@ def __init__(
         extra_argv: Iterable[str] | None = None,
         post_renderer: HelmPostRenderer | None = None,
     ) -> None:
-        self.field_set = field_set
-        self.cmd = cmd
-        self.description = description
-        self.extra_argv = tuple(extra_argv or ())
-        self.post_renderer = post_renderer
+        object.__setattr__(self, "field_set", field_set)
+        object.__setattr__(self, "cmd", cmd)
+        object.__setattr__(self, "description", description)
+        object.__setattr__(self, "extra_argv", tuple(extra_argv or ()))
+        object.__setattr__(self, "post_renderer", post_renderer)
 
     def debug_hint(self) -> str | None:
         return self.field_set.address.spec

src/python/pants/backend/helm/util_rules/tool.py

@@ -48,7 +48,6 @@
 from pants.option.subsystem import Subsystem
 from pants.util.frozendict import FrozenDict
 from pants.util.logging import LogLevel
-from pants.util.meta import frozen_after_init
 from pants.util.strutil import bullet_list, pluralize
 
 logger = logging.getLogger(__name__)
@@ -285,8 +284,7 @@ async def download_external_helm_plugin(request: ExternalHelmPluginRequest) -> H
 # ---------------------------------------------
 
 
-@frozen_after_init
-@dataclass(unsafe_hash=True)
+@dataclass(frozen=True)
 class HelmBinary:
     path: str
 
@@ -301,9 +299,9 @@ def __init__(
         local_env: Mapping[str, str],
         immutable_input_digests: Mapping[str, Digest],
     ) -> None:
-        self.path = path
-        self.immutable_input_digests = FrozenDict(immutable_input_digests)
-        self.env = FrozenDict({**helm_env, **local_env})
+        object.__setattr__(self, "path", path)
+        object.__setattr__(self, "immutable_input_digests", FrozenDict(immutable_input_digests))
+        object.__setattr__(self, "env", FrozenDict({**helm_env, **local_env}))
 
     @property
     def config_digest(self) -> Digest:
@@ -318,8 +316,7 @@ def append_only_caches(self) -> dict[str, str]:
         return {_HELM_CACHE_NAME: _HELM_CACHE_DIR}
 
 
-@frozen_after_init
-@dataclass(unsafe_hash=True)
+@dataclass(frozen=True)
 class HelmProcess:
     argv: tuple[str, ...]
     input_digest: Digest
@@ -348,17 +345,21 @@ def __init__(
         cache_scope: ProcessCacheScope | None = None,
         timeout_seconds: int | None = None,
     ):
-        self.argv = tuple(argv)
-        self.input_digest = input_digest
-        self.description = description
-        self.level = level
-        self.output_directories = tuple(output_directories or ())
-        self.output_files = tuple(output_files or ())
-        self.extra_env = FrozenDict(extra_env or {})
-        self.extra_immutable_input_digests = FrozenDict(extra_immutable_input_digests or {})
-        self.extra_append_only_caches = FrozenDict(extra_append_only_caches or {})
-        self.cache_scope = cache_scope
-        self.timeout_seconds = timeout_seconds
+        object.__setattr__(self, "argv", tuple(argv))
+        object.__setattr__(self, "input_digest", input_digest)
+        object.__setattr__(self, "description", description)
+        object.__setattr__(self, "level", level)
+        object.__setattr__(self, "output_directories", tuple(output_directories or ()))
+        object.__setattr__(self, "output_files", tuple(output_files or ()))
+        object.__setattr__(self, "extra_env", FrozenDict(extra_env or {}))
+        object.__setattr__(
+            self, "extra_immutable_input_digests", FrozenDict(extra_immutable_input_digests or {})
+        )
+        object.__setattr__(
+            self, "extra_append_only_caches", FrozenDict(extra_append_only_caches or {})
+        )
+        object.__setattr__(self, "cache_scope", cache_scope)
+        object.__setattr__(self, "timeout_seconds", timeout_seconds)
 
 
 @rule(desc="Download and configure Helm", level=LogLevel.DEBUG)

src/python/pants/backend/helm/utils/yaml.py

@@ -11,11 +11,9 @@
 
 from pants.engine.collection import Collection
 from pants.util.frozendict import FrozenDict
-from pants.util.meta import frozen_after_init
 
 
 @dataclass(unsafe_hash=True)
-@frozen_after_init
 class YamlPath:
     """Simple implementation of YAML paths using `/` syntax and being the single slash the path to
     the root."""
@@ -24,8 +22,8 @@ class YamlPath:
     _absolute: bool
 
     def __init__(self, elements: Iterable[str], *, absolute: bool) -> None:
-        self._elements = tuple(elements)
-        self._absolute = absolute
+        object.__setattr__(self, "_elements", tuple(elements))
+        object.__setattr__(self, "_absolute", absolute)
 
         if len(self._elements) == 0 and not self._absolute:
             raise ValueError("Relative YAML paths with no elements are not allowed.")
@@ -181,7 +179,7 @@ def to_json_dict(self) -> dict[str, dict[str, str]]:
         return {"paths": items_dict}
 
 
-@frozen_after_init
+@dataclass(frozen=True)
 class FrozenYamlIndex(Generic[T]):
     """Represents a frozen collection of items that is indexed by the following keys:
 
@@ -204,7 +202,7 @@ def __init__(self, other: MutableYamlIndex[T]) -> None:
                 doc_list[idx] = _YamlDocumentIndexNode(paths=FrozenDict(item_map))
 
             data[file_path] = Collection(doc_list)
-        self._data = FrozenDict(data)
+        object.__setattr__(self, "_data", FrozenDict(data))
 
     def transform_values(self, func: Callable[[T], Optional[R]]) -> FrozenYamlIndex[R]:
         """Transforms the values of the given indexed collection into those that are returned from

src/python/pants/backend/openapi/util_rules/generator_process.py

@@ -24,16 +24,14 @@
 from pants.jvm.util_rules import rules as jvm_util_rules
 from pants.util.frozendict import FrozenDict
 from pants.util.logging import LogLevel
-from pants.util.meta import frozen_after_init
 
 
 @unique
 class OpenAPIGeneratorType(Enum):
     JAVA = "java"
 
 
-@frozen_after_init
-@dataclass(unsafe_hash=True)
+@dataclass(frozen=True)
 class OpenAPIGeneratorProcess:
     argv: tuple[str, ...]
     generator_type: OpenAPIGeneratorType
@@ -64,18 +62,20 @@ def __init__(
         extra_jvm_options: Iterable[str] | None = None,
         cache_scope: ProcessCacheScope | None = None,
     ):
-        self.generator_type = generator_type
-        self.argv = tuple(argv)
-        self.input_digest = input_digest
-        self.description = description
-        self.level = level
-        self.output_directories = tuple(output_directories or ())
-        self.output_files = tuple(output_files or ())
-        self.extra_env = FrozenDict(extra_env or {})
-        self.extra_classpath_entries = tuple(extra_classpath_entries or ())
-        self.extra_immutable_input_digests = FrozenDict(extra_immutable_input_digests or {})
-        self.extra_jvm_options = tuple(extra_jvm_options or ())
-        self.cache_scope = cache_scope
+        object.__setattr__(self, "generator_type", generator_type)
+        object.__setattr__(self, "argv", tuple(argv))
+        object.__setattr__(self, "input_digest", input_digest)
+        object.__setattr__(self, "description", description)
+        object.__setattr__(self, "level", level)
+        object.__setattr__(self, "output_directories", tuple(output_directories or ()))
+        object.__setattr__(self, "output_files", tuple(output_files or ()))
+        object.__setattr__(self, "extra_env", FrozenDict(extra_env or {}))
+        object.__setattr__(self, "extra_classpath_entries", tuple(extra_classpath_entries or ()))
+        object.__setattr__(
+            self, "extra_immutable_input_digests", FrozenDict(extra_immutable_input_digests or {})
+        )
+        object.__setattr__(self, "extra_jvm_options", tuple(extra_jvm_options or ()))
+        object.__setattr__(self, "cache_scope", cache_scope)
 
 
 _GENERATOR_CLASS_NAME = "org.openapitools.codegen.OpenAPIGenerator"

src/python/pants/backend/project_info/dependents.py

@@ -14,7 +14,6 @@
 from pants.option.option_types import BoolOption
 from pants.util.frozendict import FrozenDict
 from pants.util.logging import LogLevel
-from pants.util.meta import frozen_after_init
 from pants.util.ordered_set import FrozenOrderedSet
 
 
@@ -44,8 +43,7 @@ async def map_addresses_to_dependents(all_targets: AllUnexpandedTargets) -> Addr
     )
 
 
-@frozen_after_init
-@dataclass(unsafe_hash=True)
+@dataclass(frozen=True)
 class DependentsRequest:
     addresses: FrozenOrderedSet[Address]
     transitive: bool
@@ -54,9 +52,9 @@ class DependentsRequest:
     def __init__(
         self, addresses: Iterable[Address], *, transitive: bool, include_roots: bool
     ) -> None:
-        self.addresses = FrozenOrderedSet(addresses)
-        self.transitive = transitive
-        self.include_roots = include_roots
+        object.__setattr__(self, "addresses", FrozenOrderedSet(addresses))
+        object.__setattr__(self, "transitive", transitive)
+        object.__setattr__(self, "include_roots", include_roots)
 
 
 class Dependents(DeduplicatedCollection[Address]):