Argument parsing in Command._convert_type currently supports only types whose constructor accepts a raw string (int("6"), float("3.14")). There is no way to teach the framework how to parse a complex object, such as a User looked up by display name, without monkey-patching the command internals.
The idea is to let any class act as a type resolver by implementing a resolve classmethod. The argument parser detects this interface via duck typing and delegates to it instead of calling the constructor directly. An optional registration helper on Bot could cover types you don't own.
Proposed API
class User:
@classmethod
def resolve(cls, value: str) -> Self:
return ... # build user from value
@bot.command()
async def profile(ctx, user: User):
await ctx.reply(f"Power level: {user.power_level}")# For types you don't own
@bot.type_resolver(Color)
def parse_color(value: str) -> Color:
return Color.from_hex(value)The hook sits in Command._convert_type. The resolver lookup order should be: explicit registry on Bot first, then the resolve classmethod, then the bare constructor, then a passthrough to str. Error handling is needed, a resolve that raises should probably surface as a BadArgumentError rather than silently falling back to the raw string.
Argument parsing in
Command._convert_typecurrently supports only types whose constructor accepts a raw string (int("6"),float("3.14")). There is no way to teach the framework how to parse a complex object, such as aUserlooked up by display name, without monkey-patching the command internals.The idea is to let any class act as a type resolver by implementing a
resolveclassmethod. The argument parser detects this interface via duck typing and delegates to it instead of calling the constructor directly. An optional registration helper onBotcould cover types you don't own.Proposed API
The hook sits in
Command._convert_type. The resolver lookup order should be: explicit registry onBotfirst, then theresolveclassmethod, then the bare constructor, then a passthrough tostr. Error handling is needed, aresolvethat raises should probably surface as aBadArgumentErrorrather than silently falling back to the raw string.