Reduce complexity on some of the typestring stuff.

- Refactor error messages in _to_typestring and _from_typestring to just
  print the prefix tuples instead of that custom error string.
- Create a RedisKeyOrValue type to simplify some annotations.
- Simplify partialmethod calls.
- Make the signatures for _to_typestring and _from_typestring one-liners
- Fix a typo in the errors.

1 files changed, 9 insertions, 31 deletions

diff --git a/bot/utils/redis_cache.py b/bot/utils/redis_cache.py
index a71ad2191..0b682d378 100644
--- a/bot/utils/redis_cache.py
+++ b/bot/utils/redis_cache.py
@@ -2,7 +2,6 @@ from __future__ import annotations
 
 import asyncio
 import logging
-import typing
 from functools import partialmethod
 from typing import Any, Dict, ItemsView, Optional, Tuple, Union
 
@@ -13,6 +12,7 @@ log = logging.getLogger(__name__)
 # Type aliases
 RedisKeyType = Union[str, int]
 RedisValueType = Union[str, int, float]
+RedisKeyOrValue = Union[RedisKeyType, RedisValueType]
 
 # Prefix tuples
 PrefixTuple = Tuple[Tuple[str, Any]]
@@ -26,20 +26,6 @@ KEY_PREFIXES = (
     ("s|", str),
 )
 
-# Makes a nice list like "float, int, and str"
-VALUE_TYPE_LIST = ", ".join(str(_type.__name__) for _type in typing.get_args(RedisValueType))
-VALUE_TYPE_LIST = ", and ".join(VALUE_TYPE_LIST.rsplit(", ", 1))
-
-KEY_TYPE_LIST = ", ".join(str(_type.__name__) for _type in typing.get_args(RedisKeyType))
-KEY_TYPE_LIST = ", and ".join(KEY_TYPE_LIST.rsplit(", ", 1))
-
-# Makes a list like "'f|', 'i|', and 's|'"
-VALUE_PREFIX_LIST = ", ".join([f"'{prefix}'" for prefix, _ in VALUE_PREFIXES])
-VALUE_PREFIX_LIST = ", and ".join(VALUE_PREFIX_LIST.rsplit(", ", 1))
-
-KEY_PREFIX_LIST = ", ".join([f"'{prefix}'" for prefix, _ in KEY_PREFIXES])
-KEY_PREFIX_LIST = ", and ".join(KEY_PREFIX_LIST.rsplit(", ", 1))
-
 
 class RedisCache:
     """
@@ -116,23 +102,15 @@ class RedisCache:
         self._namespace = namespace
 
     @staticmethod
-    def _to_typestring(
-            key_or_value: Union[RedisKeyType, RedisValueType],
-            prefixes: PrefixTuple,
-            types_string: str
-    ) -> str:
+    def _to_typestring(key_or_value: RedisKeyOrValue, prefixes: PrefixTuple) -> str:
         """Turn a valid Redis type into a typestring."""
         for prefix, _type in prefixes:
             if isinstance(key_or_value, _type):
                 return f"{prefix}{key_or_value}"
-        raise TypeError(f"RedisCache._from_typestring only supports the types {types_string}.")
+        raise TypeError(f"RedisCache._to_typestring only supports the following: {prefixes}.")
 
     @staticmethod
-    def _from_typestring(
-            key_or_value: Union[bytes, str],
-            prefixes: PrefixTuple,
-            prefixes_string: str,
-    ) -> Union[RedisKeyType, RedisValueType]:
+    def _from_typestring(key_or_value: Union[bytes, str], prefixes: PrefixTuple) -> RedisKeyOrValue:
         """Deserialize a typestring into a valid Redis type."""
         # Stuff that comes out of Redis will be bytestrings, so let's decode those.
         if isinstance(key_or_value, bytes):
@@ -142,7 +120,7 @@ class RedisCache:
         for prefix, _type in prefixes:
             if key_or_value.startswith(prefix):
                 return _type(key_or_value[len(prefix):])
-        raise TypeError(f"RedisCache._to_typestring only supports the prefixes {prefixes_string}.")
+        raise TypeError(f"RedisCache._from_typestring only supports the following: {prefixes}.")
 
     # Add some nice partials to call our generic typestring converters.
     # These are basically methods that will fill in some of the parameters for you, so that
@@ -150,10 +128,10 @@ class RedisCache:
     # at `prefixes` and `types_string` pre-filled.
     #
     # See https://docs.python.org/3/library/functools.html#functools.partialmethod
-    _key_to_typestring = partialmethod(_to_typestring, prefixes=KEY_PREFIXES, types_string=KEY_TYPE_LIST)
-    _value_to_typestring = partialmethod(_to_typestring, prefixes=VALUE_PREFIXES, types_string=VALUE_TYPE_LIST)
-    _key_from_typestring = partialmethod(_from_typestring, prefixes=KEY_PREFIXES, prefixes_string=KEY_PREFIX_LIST)
-    _value_from_typestring = partialmethod(_from_typestring, prefixes=VALUE_PREFIXES, prefixes_string=VALUE_PREFIX_LIST)
+    _key_to_typestring = partialmethod(_to_typestring, prefixes=KEY_PREFIXES)
+    _value_to_typestring = partialmethod(_to_typestring, prefixes=VALUE_PREFIXES)
+    _key_from_typestring = partialmethod(_from_typestring, prefixes=KEY_PREFIXES)
+    _value_from_typestring = partialmethod(_from_typestring, prefixes=VALUE_PREFIXES)
 
     def _dict_from_typestring(self, dictionary: Dict) -> Dict:
         """Turns all contents of a dict into valid Redis types."""