V2: world[instanceOf[SomeProtocol]()] and .by_default

[pauleveritt]

(Sorry, going to be a lot of questions..I have a long way to go to be ready by Monday. 🙁)
In the code below, a question marked with Q:...not sure why the .by_default registration wasn't chosen. I can fix it with with single.

@interface
class Greeter(Protocol):
    name: str


@dataclass
class FrenchCustomer:
    name: str = "French Customer"


@implements.protocol[Greeter]().by_default
@dataclass
class DefaultGreeter:
    name: str = "Default Greeter"


@implements.protocol[Greeter]().when(qualified_by=FrenchCustomer)
@dataclass
class FrenchGreeter:
    name: str = "French Greeter"


def test_world():
    # Q: Why does this match FrenchGreeter? There's no qualification.
    # Shouldn't it have matched the `.by_default`?
    greeter = world[instanceOf[Greeter]()]
    # This forces it to work:
    # greeter = world[instanceOf[Greeter]().single(qualified_by=NotQualified)]
    assert greeter.name == "French Greeter"

[Finistere]

With instanceOf[Greeter]() you're actually asking for an instance of Greeter without any constraints. So any implementation will work, FrenchGreeter included. If you want an implementation with any qualifiers, you need to add a constraint for it:

from antidote import QualifiedBy, world, instanceOf

def not_qualified(predicate: QualifiedBy | None) -> bool:
    return predicate is None

greeter = world[instanceOf[Greeter]().single(not_qualified)]

Maybe it should be there by default, not sure.