[commands] Minimise code duplication in channel converters

discord/ext/commands/converter.py

@@ -26,7 +26,7 @@ from __future__ import annotations
 
 import re
 import inspect
-from typing import TYPE_CHECKING, List, Protocol, TypeVar, Tuple, Union, runtime_checkable
+from typing import Iterable, Optional, TYPE_CHECKING, List, Protocol, Type, TypeVar, Tuple, Union, runtime_checkable
 
 import discord
 from .errors import *
@@ -72,6 +72,7 @@ def _get_from_guilds(bot, getter, argument):
 _utils_get = discord.utils.get
 T = TypeVar('T')
 T_co = TypeVar('T_co', covariant=True)
+CT = TypeVar('CT', bound=discord.abc.GuildChannel)
 
 
 @runtime_checkable
@@ -112,13 +113,13 @@ class Converter(Protocol[T_co]):
         raise NotImplementedError('Derived classes need to implement this.')
 
 
-class IDConverter(Converter[T_co]):
+_ID_REGEX = re.compile(r'([0-9]{15,20})$')
-    def __init__(self):
-        self._id_regex = re.compile(r'([0-9]{15,20})$')
-        super().__init__()
 
-    def _get_id_match(self, argument):
+
-        return self._id_regex.match(argument)
+class IDConverter(Converter[T_co]):
+    @staticmethod
+    def _get_id_match(argument):
+        return _ID_REGEX.match(argument)
 
 
 class MemberConverter(IDConverter[discord.Member]):
@@ -351,20 +352,24 @@ class TextChannelConverter(IDConverter[discord.TextChannel]):
     """
 
     async def convert(self, ctx: Context, argument: str) -> discord.TextChannel:
+        return self._resolve_channel(ctx, argument, ctx.guild.text_channels, discord.TextChannel)
+
+    @staticmethod
+    def _resolve_channel(ctx: Context, argument: str, iterable: Iterable[CT], type: Type[CT]) -> CT:
         bot = ctx.bot
 
-        match = self._get_id_match(argument) or re.match(r'<#([0-9]+)>$', argument)
+        match = IDConverter._get_id_match(argument) or re.match(r'<#([0-9]+)>$', argument)
         result = None
         guild = ctx.guild
 
         if match is None:
             # not a mention
             if guild:
-                result = discord.utils.get(guild.text_channels, name=argument)
+                result: Optional[CT] = discord.utils.get(iterable, name=argument)
             else:
 
                 def check(c):
-                    return isinstance(c, discord.TextChannel) and c.name == argument
+                    return isinstance(c, type) and c.name == argument
 
                 result = discord.utils.find(check, bot.get_all_channels())
         else:
@@ -374,7 +379,7 @@ class TextChannelConverter(IDConverter[discord.TextChannel]):
             else:
                 result = _get_from_guilds(bot, 'get_channel', channel_id)
 
-        if not isinstance(result, discord.TextChannel):
+        if not isinstance(result, type):
             raise ChannelNotFound(argument)
 
         return result
@@ -397,32 +402,7 @@ class VoiceChannelConverter(IDConverter[discord.VoiceChannel]):
     """
 
     async def convert(self, ctx: Context, argument: str) -> discord.VoiceChannel:
-        bot = ctx.bot
+        return TextChannelConverter._resolve_channel(ctx, argument, ctx.guild.voice_channels, discord.VoiceChannel)
-        match = self._get_id_match(argument) or re.match(r'<#([0-9]+)>$', argument)
-        result = None
-        guild = ctx.guild
-
-        if match is None:
-            # not a mention
-            if guild:
-                result = discord.utils.get(guild.voice_channels, name=argument)
-            else:
-
-                def check(c):
-                    return isinstance(c, discord.VoiceChannel) and c.name == argument
-
-                result = discord.utils.find(check, bot.get_all_channels())
-        else:
-            channel_id = int(match.group(1))
-            if guild:
-                result = guild.get_channel(channel_id)
-            else:
-                result = _get_from_guilds(bot, 'get_channel', channel_id)
-
-        if not isinstance(result, discord.VoiceChannel):
-            raise ChannelNotFound(argument)
-
-        return result
 
 
 class StageChannelConverter(IDConverter[discord.StageChannel]):
@@ -441,32 +421,7 @@ class StageChannelConverter(IDConverter[discord.StageChannel]):
     """
 
     async def convert(self, ctx: Context, argument: str) -> discord.StageChannel:
-        bot = ctx.bot
+        return TextChannelConverter._resolve_channel(ctx, argument, ctx.guild.stage_channels, discord.StageChannel)
-        match = self._get_id_match(argument) or re.match(r'<#([0-9]+)>$', argument)
-        result = None
-        guild = ctx.guild
-
-        if match is None:
-            # not a mention
-            if guild:
-                result = discord.utils.get(guild.stage_channels, name=argument)
-            else:
-
-                def check(c):
-                    return isinstance(c, discord.StageChannel) and c.name == argument
-
-                result = discord.utils.find(check, bot.get_all_channels())
-        else:
-            channel_id = int(match.group(1))
-            if guild:
-                result = guild.get_channel(channel_id)
-            else:
-                result = _get_from_guilds(bot, 'get_channel', channel_id)
-
-        if not isinstance(result, discord.StageChannel):
-            raise ChannelNotFound(argument)
-
-        return result
 
 
 class CategoryChannelConverter(IDConverter[discord.CategoryChannel]):
@@ -486,33 +441,7 @@ class CategoryChannelConverter(IDConverter[discord.CategoryChannel]):
     """
 
     async def convert(self, ctx: Context, argument: str) -> discord.CategoryChannel:
-        bot = ctx.bot
+        return TextChannelConverter._resolve_channel(ctx, argument, ctx.guild.categories, discord.CategoryChannel)
-
-        match = self._get_id_match(argument) or re.match(r'<#([0-9]+)>$', argument)
-        result = None
-        guild = ctx.guild
-
-        if match is None:
-            # not a mention
-            if guild:
-                result = discord.utils.get(guild.categories, name=argument)
-            else:
-
-                def check(c):
-                    return isinstance(c, discord.CategoryChannel) and c.name == argument
-
-                result = discord.utils.find(check, bot.get_all_channels())
-        else:
-            channel_id = int(match.group(1))
-            if guild:
-                result = guild.get_channel(channel_id)
-            else:
-                result = _get_from_guilds(bot, 'get_channel', channel_id)
-
-        if not isinstance(result, discord.CategoryChannel):
-            raise ChannelNotFound(argument)
-
-        return result
 
 
 class StoreChannelConverter(IDConverter[discord.StoreChannel]):
@@ -531,32 +460,7 @@ class StoreChannelConverter(IDConverter[discord.StoreChannel]):
     """
 
     async def convert(self, ctx: Context, argument: str) -> discord.StoreChannel:
-        bot = ctx.bot
+        return TextChannelConverter._resolve_channel(ctx, argument, ctx.guild.channels, discord.StoreChannel)
-        match = self._get_id_match(argument) or re.match(r'<#([0-9]+)>$', argument)
-        result = None
-        guild = ctx.guild
-
-        if match is None:
-            # not a mention
-            if guild:
-                result = discord.utils.get(guild.channels, name=argument)
-            else:
-
-                def check(c):
-                    return isinstance(c, discord.StoreChannel) and c.name == argument
-
-                result = discord.utils.find(check, bot.get_all_channels())
-        else:
-            channel_id = int(match.group(1))
-            if guild:
-                result = guild.get_channel(channel_id)
-            else:
-                result = _get_from_guilds(bot, 'get_channel', channel_id)
-
-        if not isinstance(result, discord.StoreChannel):
-            raise ChannelNotFound(argument)
-
-        return result
 
 
 class ColourConverter(Converter[discord.Colour]):
@@ -865,10 +769,12 @@ class clean_content(Converter[str]):
                 r = _find(_id)
                 return '@' + r.name if r else '@deleted-role'
 
+            # fmt: off
             transformations.update(
                 (f'<@&{role_id}>', resolve_role(role_id))
                 for role_id in message.raw_role_mentions
-            )  # fmt: off
+            )
+            # fmt: on
 
         def repl(obj):
             return transformations.get(obj.group(0), '')