Add type back to attrs.field() for use in attrs.make_class()

[rouge8]

I'm using attrs.make_class() to dynamically construct a class based on other attrs classes, and it would be nice to be able to specify the type of the fields on the generated class using attrs.field() instead of attr.ib(). In other words, this works:

fields = {
    field.name: attr.ib(type=field.type)
    for field in itertools.chain.from_iterable(
        attrs.fields(t) for t in SOME_ATTRS_CLASSES
    )
    if not field.name.startswith("_")
}

MyClass = attrs.make_class("MyClass", fields)

but this does not:

fields = {
    field.name: attrs.field(type=field.type)
    for field in itertools.chain.from_iterable(
        attrs.fields(t) for t in SOME_ATTRS_CLASSES
    )
    if not field.name.startswith("_")
}

MyClass = attrs.make_class("MyClass", fields)

[hynek]

Aw man yeah when I celebrated to get rid of that, I forgot about make_class. 🙈

[chrysle]

I'm working on the implementation.

[hynek]

Given that no type checker cares about make_class() as far as I can tell (I tried to get it to fail by passing wrong arguments to a make_class-borne class), would you mind sharing the utility you're getting out of this?

[rouge8]

I ended up not needing make_class(), but I wanted type for our in-house structuring library, similar to cattrs.

[hynek]

So metadata, gotcha!

I'm asking because I want to put a fat warning next to the argument.

[sscherfke]

This would also be nice for Typed Settings :-)

[hynek]

@sscherfke well good news in #1107 ;)

[sscherfke]

woop woop \o/