[commands] Allow Greedy to potentially maintain state between calls

discord/ext/commands/converter.py

@@ -1039,6 +1039,17 @@ class Greedy(List[T]):
 
         return cls(converter=converter)
 
+    @property
+    def constructed_converter(self) -> Any:
+        # Only construct a converter once in order to maintain state between convert calls
+        if (
+            inspect.isclass(self.converter)
+            and issubclass(self.converter, Converter)
+            and not inspect.ismethod(self.converter.convert)
+        ):
+            return self.converter()
+        return self.converter
+
 
 if TYPE_CHECKING:
     from typing_extensions import Annotated as Range

discord/ext/commands/core.py

@@ -657,14 +657,14 @@ class Command(_BaseCommand, Generic[CogT, P, T]):
                 return list(attachments)
 
             if param.kind in (param.POSITIONAL_OR_KEYWORD, param.POSITIONAL_ONLY):
-                return await self._transform_greedy_pos(ctx, param, param.required, converter.converter)
+                return await self._transform_greedy_pos(ctx, param, param.required, converter.constructed_converter)
             elif param.kind == param.VAR_POSITIONAL:
-                return await self._transform_greedy_var_pos(ctx, param, converter.converter)
+                return await self._transform_greedy_var_pos(ctx, param, converter.constructed_converter)
             else:
                 # if we're here, then it's a KEYWORD_ONLY param type
                 # since this is mostly useless, we'll helpfully transform Greedy[X]
                 # into just X and do the parsing that way.
-                converter = converter.converter
+                converter = converter.constructed_converter
 
         # Try to detect Optional[discord.Attachment] or discord.Attachment special converter
         if converter is discord.Attachment: