From f21abf62d4d1470c4deaec3ea8314ca64edbfc3e Mon Sep 17 00:00:00 2001
From: Adam Hopkins <adam@amhopkins.com>
Date: Tue, 21 Dec 2021 00:39:07 +0200
Subject: [PATCH] Simplify converter registration

---
 sanic/config.py      | 29 ++++++++++++-----------------
 tests/test_config.py |  6 ++++--
 2 files changed, 16 insertions(+), 19 deletions(-)

diff --git a/sanic/config.py b/sanic/config.py
index 7eb5ab94ae..d4057a71a1 100644
--- a/sanic/config.py
+++ b/sanic/config.py
@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-from collections import deque
 from inspect import getmembers, isclass, isdatadescriptor
 from os import environ
 from pathlib import Path
@@ -49,16 +48,6 @@
 DEPRECATED_CONFIG = ("SERVER_RUNNING", "RELOADER_PROCESS", "RELOADED_FILES")
 
 
-class CastRegistry(deque):
-    def add(self, cast: Callable[[str], Any]) -> None:
-        if cast in self:
-            error_logger.warning(
-                f"Type cast '{cast.__name__}' has already been registered"
-            )
-            return None
-        self.appendleft(cast)
-
-
 class DescriptorMeta(type):
     def __init__(cls, *_):
         cls.__setters__ = {name for name, _ in getmembers(cls, cls._is_setter)}
@@ -106,11 +95,12 @@ def __init__(
         defaults = defaults or {}
         super().__init__({**DEFAULT_CONFIG, **defaults})
 
-        self._cast_registry = CastRegistry((int, float, str_to_bool, str))
+        self._converters = [str, str_to_bool, float, int]
         self._LOGO = ""
 
         if converters:
-            self.register_type(*converters)
+            for converter in converters:
+                self.register_type(converter)
 
         if keep_alive is not None:
             self.KEEP_ALIVE = keep_alive
@@ -244,7 +234,7 @@ def __init__(self, name) -> None:
 
             _, config_key = key.split(prefix, 1)
 
-            for converter in self._cast_registry:
+            for converter in reversed(self._converters):
                 try:
                     self[config_key] = converter(value)
                     break
@@ -320,11 +310,16 @@ class C:
 
     load = update_config
 
-    def register_type(self, *cast: Callable[[str], Any]) -> None:
+    def register_type(self, converter: Callable[[str], Any]) -> None:
         """
         Allows for adding custom function to cast from a string value to any
         other type. The function should raise ValueError if it is not the
         correct type.
         """
-        for item in cast:
-            self._cast_registry.add(item)
+        if converter in self._converters:
+            error_logger.warning(
+                f"Configuration value converter '{converter.__name__}' has "
+                "already been registered"
+            )
+            return
+        self._converters.append(converter)
diff --git a/tests/test_config.py b/tests/test_config.py
index 41e36f105a..7c5bab05cd 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -158,14 +158,16 @@ def test_add_converter_multiple_times(caplog):
     def converter():
         ...
 
-    message = "Type cast 'converter' has already been registered"
+    message = (
+        "Configuration value converter 'converter' has already been registered"
+    )
     config = Config()
     config.register_type(converter)
     with caplog.at_level(logging.WARNING):
         config.register_type(converter)
 
     assert ("sanic.error", logging.WARNING, message) in caplog.record_tuples
-    assert len(config._cast_registry) == 5
+    assert len(config._converters) == 5
 
 
 def test_load_from_file(app):