Replace dataclasses with attrs and slotted classes

Signed-off-by: Sergey Vasilyev <nolar@nolar.info>

Author: nolar

kopf/_cogs/configs/configuration.py

@@ -26,15 +26,16 @@
     used interchangeably -- but so that it is understandable what is meant.
 """
 import concurrent.futures
-import dataclasses
 import logging
 from typing import Iterable, Optional, Union
 
+import attrs
+
 from kopf._cogs.configs import diffbase, progress
 from kopf._cogs.structs import reviews
 
 
-@dataclasses.dataclass
+@attrs.define
 class ProcessSettings:
     """
     Settings for Kopf's OS processes: e.g. when started via CLI as `kopf run`.
@@ -59,7 +60,7 @@ class ProcessSettings:
     """
 
 
-@dataclasses.dataclass
+@attrs.define
 class PostingSettings:
 
     enabled: bool = True
@@ -81,7 +82,7 @@ class PostingSettings:
     """
 
 
-@dataclasses.dataclass
+@attrs.define
 class PeeringSettings:
 
     name: str = 'default'
@@ -162,7 +163,7 @@ def namespaced(self, value: bool) -> None:
         self.clusterwide = not value
 
 
-@dataclasses.dataclass
+@attrs.define
 class WatchingSettings:
 
     server_timeout: Optional[float] = None
@@ -187,7 +188,7 @@ class WatchingSettings:
     """
 
 
-@dataclasses.dataclass
+@attrs.define
 class BatchingSettings:
     """
     Settings for how raw events are batched and processed.
@@ -224,7 +225,7 @@ class BatchingSettings:
     """
 
 
-@dataclasses.dataclass
+@attrs.define
 class ScanningSettings:
     """
     Settings for dynamic runtime observation of the cluster's setup.
@@ -249,7 +250,7 @@ class ScanningSettings:
     """
 
 
-@dataclasses.dataclass
+@attrs.define
 class AdmissionSettings:
 
     server: Optional[reviews.WebhookServerProtocol] = None
@@ -290,14 +291,13 @@ class AdmissionSettings:
     """
 
 
-@dataclasses.dataclass
+@attrs.define
 class ExecutionSettings:
     """
     Settings for synchronous handlers execution (e.g. thread-/process-pools).
     """
 
-    executor: concurrent.futures.Executor = dataclasses.field(
-        default_factory=concurrent.futures.ThreadPoolExecutor)
+    executor: concurrent.futures.Executor = attrs.Factory(concurrent.futures.ThreadPoolExecutor)
     """
     The executor to be used for synchronous handler invocation.
 
@@ -328,7 +328,7 @@ def max_workers(self, value: int) -> None:
             raise TypeError("Current executor does not support `max_workers`.")
 
 
-@dataclasses.dataclass
+@attrs.define
 class NetworkingSettings:
 
     request_timeout: Optional[float] = 5 * 60  # == aiohttp.client.DEFAULT_TIMEOUT
@@ -353,7 +353,7 @@ class NetworkingSettings:
     """
 
 
-@dataclasses.dataclass
+@attrs.define
 class PersistenceSettings:
 
     finalizer: str = 'kopf.zalando.org/KopfFinalizerMarker'
@@ -362,20 +362,18 @@ class PersistenceSettings:
     from being deleted without framework's/operator's permission.
     """
 
-    progress_storage: progress.ProgressStorage = dataclasses.field(
-        default_factory=progress.SmartProgressStorage)
+    progress_storage: progress.ProgressStorage = attrs.Factory(progress.SmartProgressStorage)
     """
     How to persist the handlers' state between multiple handling cycles.
     """
 
-    diffbase_storage: diffbase.DiffBaseStorage = dataclasses.field(
-        default_factory=diffbase.AnnotationsDiffBaseStorage)
+    diffbase_storage: diffbase.DiffBaseStorage = attrs.Factory(diffbase.AnnotationsDiffBaseStorage)
     """
     How the resource's essence (non-technical, contentful fields) are stored.
     """
 
 
-@dataclasses.dataclass
+@attrs.define
 class BackgroundSettings:
     """
     Settings for background routines in general, daemons & timers specifically.
@@ -434,16 +432,16 @@ class BackgroundSettings:
     """
 
 
-@dataclasses.dataclass
+@attrs.define
 class OperatorSettings:
-    process: ProcessSettings = dataclasses.field(default_factory=ProcessSettings)
-    posting: PostingSettings = dataclasses.field(default_factory=PostingSettings)
-    peering: PeeringSettings = dataclasses.field(default_factory=PeeringSettings)
-    watching: WatchingSettings = dataclasses.field(default_factory=WatchingSettings)
-    batching: BatchingSettings = dataclasses.field(default_factory=BatchingSettings)
-    scanning: ScanningSettings = dataclasses.field(default_factory=ScanningSettings)
-    admission: AdmissionSettings =dataclasses.field(default_factory=AdmissionSettings)
-    execution: ExecutionSettings = dataclasses.field(default_factory=ExecutionSettings)
-    background: BackgroundSettings = dataclasses.field(default_factory=BackgroundSettings)
-    networking: NetworkingSettings = dataclasses.field(default_factory=NetworkingSettings)
-    persistence: PersistenceSettings = dataclasses.field(default_factory=PersistenceSettings)
+    process: ProcessSettings = attrs.Factory(ProcessSettings)
+    posting: PostingSettings = attrs.Factory(PostingSettings)
+    peering: PeeringSettings = attrs.Factory(PeeringSettings)
+    watching: WatchingSettings = attrs.Factory(WatchingSettings)
+    batching: BatchingSettings = attrs.Factory(BatchingSettings)
+    scanning: ScanningSettings = attrs.Factory(ScanningSettings)
+    admission: AdmissionSettings =attrs.Factory(AdmissionSettings)
+    execution: ExecutionSettings = attrs.Factory(ExecutionSettings)
+    background: BackgroundSettings = attrs.Factory(BackgroundSettings)
+    networking: NetworkingSettings = attrs.Factory(NetworkingSettings)
+    persistence: PersistenceSettings = attrs.Factory(PersistenceSettings)

kopf/_cogs/structs/credentials.py

@@ -25,12 +25,13 @@
 """
 import asyncio
 import collections
-import dataclasses
 import datetime
 import random
 from typing import AsyncIterable, AsyncIterator, Callable, Dict, List, \
                    Mapping, NewType, Optional, Tuple, TypeVar, cast
 
+import attrs
+
 from kopf._cogs.aiokits import aiotoggles
 
 
@@ -42,7 +43,7 @@ class AccessError(Exception):
     """ Raised when the operator cannot access the cluster API. """
 
 
-@dataclasses.dataclass(frozen=True)
+@attrs.define(frozen=True)
 class ConnectionInfo:
     """
     A single endpoint with specific credentials and connection flags to use.
@@ -70,7 +71,7 @@ class ConnectionInfo:
 VaultKey = NewType('VaultKey', str)
 
 
-@dataclasses.dataclass
+@attrs.define
 class VaultItem:
     """
     The actual item stored in the vault. It is never exposed externally.

kopf/_cogs/structs/references.py

@@ -1,12 +1,13 @@
 import asyncio
-import dataclasses
 import enum
 import fnmatch
 import re
 import urllib.parse
 from typing import Collection, FrozenSet, Iterable, Iterator, List, Mapping, \
                    MutableMapping, NewType, Optional, Pattern, Set, Union
 
+import attrs
+
 # A namespace specification with globs, negations, and some minimal syntax; see `match_namespace()`.
 # Regexps are also supported if pre-compiled from the code, not from the CLI options as raw strings.
 NamespacePattern = Union[str, Pattern]
@@ -100,7 +101,7 @@ def match_namespace(name: NamespaceName, pattern: NamespacePattern) -> bool:
 K8S_VERSION_PATTERN = re.compile(r'^v\d+(?:(?:alpha|beta)\d+)?$')
 
 
-@dataclasses.dataclass(frozen=True, eq=False, repr=False)
+@attrs.define(frozen=True)
 class Resource:
     """
     A reference to a very specific custom or built-in resource kind.
@@ -250,7 +251,7 @@ class Marker(enum.Enum):
 EVERYTHING = Marker.EVERYTHING
 
 
-@dataclasses.dataclass(frozen=True)
+@attrs.define(frozen=True, init=False)
 class Selector:
     """
     A resource specification that can match several resource kinds.
@@ -265,61 +266,59 @@ class Selector:
     resource kinds. Even if those specifications look very concrete and allow
     no variations, they still remain specifications.
     """
-
-    arg1: dataclasses.InitVar[Union[None, str, Marker]] = None
-    arg2: dataclasses.InitVar[Union[None, str, Marker]] = None
-    arg3: dataclasses.InitVar[Union[None, str, Marker]] = None
-    argN: dataclasses.InitVar[None] = None  # a runtime guard against too many positional arguments
-
     group: Optional[str] = None
     version: Optional[str] = None
-
     kind: Optional[str] = None
     plural: Optional[str] = None
     singular: Optional[str] = None
     shortcut: Optional[str] = None
     category: Optional[str] = None
     any_name: Optional[Union[str, Marker]] = None
 
-    def __post_init__(
+    def __init__(
             self,
-            arg1: Union[None, str, Marker],
-            arg2: Union[None, str, Marker],
-            arg3: Union[None, str, Marker],
-            argN: None,  # a runtime guard against too many positional arguments
+            arg1: Union[None, str, Marker] = None,
+            arg2: Union[None, str, Marker] = None,
+            arg3: Union[None, str, Marker] = None,
+            *,
+            group: Optional[str] = None,
+            version: Optional[str] = None,
+            kind: Optional[str] = None,
+            plural: Optional[str] = None,
+            singular: Optional[str] = None,
+            shortcut: Optional[str] = None,
+            category: Optional[str] = None,
+            any_name: Optional[Union[str, Marker]] = None,
     ) -> None:
+        super().__init__()
 
-        # Since the class is frozen & read-only, post-creation field adjustment is done via a hack.
-        # This is the same hack as used in the frozen dataclasses to initialise their fields.
-        if argN is not None:
-            raise TypeError("Too many positional arguments. Max 3 positional args are accepted.")
+        if arg3 is not None and not isinstance(arg1, Marker) and not isinstance(arg2, Marker):
+            group, version, any_name = arg1, arg2, arg3
         elif arg3 is not None:
-            object.__setattr__(self, 'group', arg1)
-            object.__setattr__(self, 'version', arg2)
-            object.__setattr__(self, 'any_name', arg3)
+            raise TypeError("Only the last positional argument can be an everything-marker.")
         elif arg2 is not None and isinstance(arg1, str) and '/' in arg1:
-            object.__setattr__(self, 'group', arg1.rsplit('/', 1)[0])
-            object.__setattr__(self, 'version', arg1.rsplit('/')[-1])
-            object.__setattr__(self, 'any_name', arg2)
-        elif arg2 is not None and arg1 == 'v1':
-            object.__setattr__(self, 'group', '')
-            object.__setattr__(self, 'version', arg1)
-            object.__setattr__(self, 'any_name', arg2)
-        elif arg2 is not None:
-            object.__setattr__(self, 'group', arg1)
-            object.__setattr__(self, 'any_name', arg2)
+            group, version = arg1.rsplit('/', 1)
+            any_name = arg2
+        elif arg2 is not None and isinstance(arg1, str) and arg1 == 'v1':
+            group, version, any_name = '', arg1, arg2
+        elif arg2 is not None and not isinstance(arg1, Marker):
+            group, any_name = arg1, arg2
         elif arg1 is not None and isinstance(arg1, Marker):
-            object.__setattr__(self, 'any_name', arg1)
+            any_name = arg1
         elif arg1 is not None and '.' in arg1 and K8S_VERSION_PATTERN.match(arg1.split('.')[1]):
             if len(arg1.split('.')) >= 3:
-                object.__setattr__(self, 'group', arg1.split('.', 2)[2])
-            object.__setattr__(self, 'version', arg1.split('.')[1])
-            object.__setattr__(self, 'any_name', arg1.split('.')[0])
+                any_name, version, group = arg1.split('.', 2)
+            else:
+                any_name, version = arg1.split('.')
         elif arg1 is not None and '.' in arg1:
-            object.__setattr__(self, 'group', arg1.split('.', 1)[1])
-            object.__setattr__(self, 'any_name', arg1.split('.')[0])
+            any_name, group = arg1.split('.', 1)
         elif arg1 is not None:
-            object.__setattr__(self, 'any_name', arg1)
+            any_name = arg1
+
+        self.__attrs_init__(
+            group=group, version=version, kind=kind, plural=plural, singular=singular,
+            shortcut=shortcut, category=category, any_name=any_name
+        )
 
         # Verify that explicit & interpreted arguments have produced an unambiguous specification.
         names = [self.kind, self.plural, self.singular, self.shortcut, self.category, self.any_name]
@@ -336,8 +335,7 @@ def __post_init__(
             raise TypeError("Names must not be empty strings; either None or specific strings.")
 
     def __repr__(self) -> str:
-        kwargs = {f.name: getattr(self, f.name) for f in dataclasses.fields(self)}
-        kwtext = ', '.join([f'{key!s}={val!r}' for key, val in kwargs.items() if val is not None])
+        kwtext = ', '.join([f'{k!s}={v!r}' for k, v in attrs.asdict(self).items() if v is not None])
         clsname = self.__class__.__name__
         return f'{clsname}({kwtext})'
 
@@ -473,7 +471,7 @@ async def wait_for(
         return self[selector]
 
 
-@dataclasses.dataclass(frozen=True)
+@attrs.define(frozen=True)
 class Insights:
     """
     Actual resources & namespaces served by the operator.
@@ -483,15 +481,15 @@ class Insights:
     # - **Indexed** resources block the operator startup until all objects are initially indexed.
     # - **Watched** resources spawn the watch-streams; the set excludes all webhook-only resources.
     # - **Webhook** resources are served via webhooks; the set excludes all watch-only resources.
-    webhook_resources: Set[Resource] = dataclasses.field(default_factory=set)
-    indexed_resources: Set[Resource] = dataclasses.field(default_factory=set)
-    watched_resources: Set[Resource] = dataclasses.field(default_factory=set)
-    namespaces: Set[Namespace] = dataclasses.field(default_factory=set)
-    backbone: Backbone = dataclasses.field(default_factory=Backbone)
+    webhook_resources: Set[Resource] = attrs.field(factory=set)
+    indexed_resources: Set[Resource] = attrs.field(factory=set)
+    watched_resources: Set[Resource] = attrs.field(factory=set)
+    namespaces: Set[Namespace] = attrs.field(factory=set)
+    backbone: Backbone = attrs.field(factory=Backbone)
 
     # Signalled when anything changes in the insights.
-    revised: asyncio.Condition = dataclasses.field(default_factory=asyncio.Condition)
+    revised: asyncio.Condition = attrs.field(factory=asyncio.Condition)
 
     # The flags that are set after the initial listing is finished. Not cleared afterwards.
-    ready_namespaces: asyncio.Event = dataclasses.field(default_factory=asyncio.Event)
-    ready_resources: asyncio.Event = dataclasses.field(default_factory=asyncio.Event)
+    ready_namespaces: asyncio.Event = attrs.field(factory=asyncio.Event)
+    ready_resources: asyncio.Event = attrs.field(factory=asyncio.Event)