chore: add missing __slots__ for various mappings.

These always should've been there, it's just older
code from before the slotting work.  Being the underlying
classes *are* slotted, slot these.

Note: this can result in exposing bugs in code deriving
from these classes, which was setting it's own __slots__.
Effectively the __dict__ just got removed, so their class
*will* do what they intended- be slotted.  If there code
didn't account for all needed slots, it'll break.

Nothing I've audited is at risk, and their code would
be buggy anyways, so this change is safe.

Signed-off-by: Brian Harring <ferringb@gmail.com>

Author: ferringb

src/pkgcore/binpkg/remote.py

@@ -36,6 +36,8 @@ class CacheEntry(StackedDict):
     returns None instead. This is likely to be changed.
     """
 
+    __slots__ = ()
+
     def pop(self, key, default=None):
         try:
             return self[key]

src/pkgcore/binpkg/repository.py

@@ -184,6 +184,7 @@ def __contains__(self, key):
 
 
 class StackedCache(StackedDict):
+    __slots__ = ()
     __externally_mutable__ = True
 
     def __delitem__(self, key):

src/pkgcore/config/central.py

@@ -32,6 +32,7 @@ class _ConfigMapping(mappings.DictMixin):
     any of them are remote!
     """
 
+    __slots__ = ("manager", "typename")
     typename: str
 
     def __init__(self, manager, typename: str) -> None:

src/pkgcore/ebuild/misc.py

@@ -141,7 +141,7 @@ def incremental_expansion_license(
 
 
 class IncrementalsDict(mappings.DictMixin):
-    disable_py3k_rewriting = True
+    __slots__ = ("_dict", "_incrementals")
 
     def __init__(self, incrementals, **kwds):
         self._incrementals = incrementals

src/pkgcore/ebuild/portage_conf.py

@@ -93,6 +93,7 @@ def parse_file(self, f, reset=True):
 class PortageConfig(DictMixin):
     """Support for portage's config file layout."""
 
+    __slots__ = ("_config", "dir", "root", "features")
     _supported_repo_types = {}
 
     def __init__(self, location=None, profile_override=None, **kwargs):

src/pkgcore/repository/prototype.py

@@ -4,8 +4,8 @@
 
 __all__ = ("CategoryLazyFrozenSet", "PackageMapping", "VersionMapping", "tree")
 
-from pathlib import Path
 import typing
+from pathlib import Path
 
 from snakeoil.klass import jit_attr
 from snakeoil.mappings import DictMixin, LazyValDict
@@ -42,6 +42,8 @@ def force_regen(self):
 
 
 class PackageMapping(DictMixin):
+    __slots__ = ("_cache", "_parent", "_pull_vals")
+
     def __init__(self, parent_mapping, pull_vals):
         self._cache = {}
         self._parent = parent_mapping
@@ -67,6 +69,8 @@ def force_regen(self, cat):
 
 
 class VersionMapping(DictMixin):
+    __slots__ = ("_cache", "_parent", "_pull_vals")
+
     def __init__(self, parent_mapping, pull_vals):
         self._cache = {}
         self._parent = parent_mapping

src/pkgcore/repository/util.py

@@ -67,6 +67,8 @@ class RepositoryGroup(DictMixin):
         combined: combined repo, if None a multiplex repo is created
     """
 
+    __slots__ = ("repos", "combined")
+
     __externally_mutable__ = False
 
     def __init__(self, repos=(), combined=None):

src/pkgcore/scripts/pclean.py

@@ -257,6 +257,8 @@ def _setup_restrictions(namespace):
 class _UnfilteredRepos(DictMixin):
     """Generate custom, unfiltered repos on demand."""
 
+    __slots__ = ("domain", "unfiltered_repos")
+
     _supported_attrs = {
         "pkg_masks",
         "pkg_unmasks",