Fixes for more issues uncovered by PyPy.

* Exceptions: Ensure that attributes which are mutated by the PyPy
  runtime are actually mutable.

* Classes: Ensure that protocol classes (descendents of ABC) allow their
  ABC machinery to be mutated after initialization. PyPy performs
  replacement on internally-mutable collections rather than clearing and
  repopulating them.

Also,

* Exceptions: Expose common constants for mutable and visible
  attributes so that they can be reused downstream.

* Nomina: Expose 'is_public_identifier' for reuse downstream.

Author: emcd

sources/classcore/exceptions.py

@@ -22,12 +22,20 @@
 
 
 from . import __
+from . import nomina as _nomina
 from . import standard as _standard
 
 
+exception_mutables_default = (
+    '__cause__', '__context__', '__suppress_context__', '__traceback__' )
+exception_visibles_default = (
+    *exception_mutables_default, _nomina.is_public_identifier )
+
+
 class Omniexception(
     _standard.Object, BaseException,
-    instances_visibles = ( '__cause__', '__context__' ),
+    instances_mutables = exception_mutables_default,
+    instances_visibles = exception_visibles_default,
 ):
     ''' Base exception for package. '''
 

sources/classcore/nomina.py

@@ -204,3 +204,8 @@
     ],
     __.ddoc.Doc( ''' Initializer to use with metaclass. ''' ),
 ]
+
+
+def is_public_identifier( name: str ) -> bool:
+    ''' Is Python identifier public? '''
+    return not name.startswith( '_' )

sources/classcore/standard/__.py

@@ -20,13 +20,11 @@
 
 ''' Common constants, imports, and utilities. '''
 
+# ruff: noqa: F403
 
-from ..__ import * # noqa: F403
 
-
-def is_public_identifier( name: str ) -> bool:
-    ''' Is Python identifier public? '''
-    return not name.startswith( '_' )
+from ..__ import *
+from ..nomina import is_public_identifier
 
 
 def provide_error_class( name: str ) -> type[ Exception ]:

sources/classcore/standard/classes.py

@@ -205,7 +205,16 @@ class DataclassObjectMutable( metaclass = DataclassMutable ):
         'class instance conceal' )
 
 
-class Protocol( __.typx.Protocol, metaclass = ProtocolClass ):
+class Protocol(
+    __.typx.Protocol,
+    metaclass = ProtocolClass,
+    class_mutables = (
+        '_abc_cache',
+        '_abc_negative_cache',
+        '_abc_negative_cache_version',
+        '_abc_registry',
+    ),
+):
     ''' Standard base protocol class. '''
 
     _dynadoc_fragments_ = (
@@ -215,7 +224,15 @@ class Protocol( __.typx.Protocol, metaclass = ProtocolClass ):
 
 
 class ProtocolMutable(
-    __.typx.Protocol, metaclass = ProtocolClass, instances_mutables = '*'
+    __.typx.Protocol,
+    metaclass = ProtocolClass,
+    class_mutables = (
+        '_abc_cache',
+        '_abc_negative_cache',
+        '_abc_negative_cache_version',
+        '_abc_registry',
+    ),
+    instances_mutables = '*',
 ):
     ''' Base protocol class with mutable instance attributes. '''
 
@@ -226,7 +243,14 @@ class ProtocolMutable(
 
 
 class DataclassProtocol(
-    __.typx.Protocol, metaclass = ProtocolDataclass,
+    __.typx.Protocol,
+    metaclass = ProtocolDataclass,
+    class_mutables = (
+        '_abc_cache',
+        '_abc_negative_cache',
+        '_abc_negative_cache_version',
+        '_abc_registry',
+    ),
 ):
     ''' Standard base protocol dataclass. '''
 
@@ -237,7 +261,14 @@ class DataclassProtocol(
 
 
 class DataclassProtocolMutable(
-    __.typx.Protocol, metaclass = ProtocolDataclassMutable,
+    __.typx.Protocol,
+    metaclass = ProtocolDataclassMutable,
+    class_mutables = (
+        '_abc_cache',
+        '_abc_negative_cache',
+        '_abc_negative_cache_version',
+        '_abc_registry',
+    ),
 ):
     ''' Base protocol dataclass with mutable instance attributes. '''