Allow `date`, `datetime`, `time` for `ge`, `gt`, `le`, `lt`

[alexei]

Description

Currently the ge, gt, le, lt constraints are limited to ints and floats, but dates, datetimes and times are comparable as well:

now = datetime.now(timezone.utc)
yesterday = now - timedelta(days=1)
tomorrow = now + timedelta(days=1)
assert yesterday <= now <= tomorrow  # True

This would enable constraints like:

class Event(Struct):
    from_date: Annotated[datetime, msgspec.Meta(gt=...)]
    to_date: Annotated[datetime, msgspec.Meta(gt=...)]

[jcrist]

Thanks for opening this, this is definitely a feature that makes sense to add. Tossing it on the todo list.

[alexei]

Out of curiosity, do these constraints need to be implemented for each type? I was looking over the list of supported types and realized decimals, strings and UUIDs can be compared as well, and just about anything that implements the comparison magic methods.

[jcrist]

Currently yes. For ints/floats a type-specific implementation can be much more efficient than a generic one.

For more complicated types like uuids/decimals/... there may be negligible benefits for implementing them in native code; we might be better served by using a generic implementation here.