https://docs.python.org/3/library/dataclasses.html#module-dataclasses

`make_dataclass` takes a `field` parameter, which is an iterable whose entries may be tuples of `(name, type)` or `(name, type, dataclasses.Field)`.  However, an exception is thrown if such tuples are provided in a particular order.  Example:


from dataclasses import field, make_dataclass

fieldspec1 = ('field1', str)
fieldspec2 = ('field2', str, field(default='Hello'))

MyDc1 = make_dataclass('MyDc1', [fieldspec1, fieldspec2]) # Ok
MyDc2 = make_dataclass('MyDc2', [fieldspec2, fieldspec1]) # TypeError

I am guessing this is not intentional...

Isn't this error that you're providing a field without a default value after one with a default value?

What's the exception look like?

TypeError: non-default argument 'field1' follows default argument

You are right.  For some reason I believed it would automatically gather the required fields first when creating the new class' signature.

No problem!

It can't reorder fields, because you might not be passing them by name. There's some discussion about requiring keyword-only parameters, in which case what you're doing would work (as long as they were keyword-only params).

Yes, that makes sense. Thank you!

On Wed, May 27, 2020, 1:40 PM Eric V. Smith <report@bugs.python.org> wrote:

>
> Eric V. Smith <eric@trueblade.com> added the comment:
>
> No problem!
>
> It can't reorder fields, because you might not be passing them by name.
> There's some discussion about requiring keyword-only parameters, in which
> case what you're doing would work (as long as they were keyword-only
> params).
>
> ----------
> resolution:  -> not a bug
>
> _______________________________________
> Python tracker <report@bugs.python.org>
> <https://bugs.python.org/issue40796>
> _______________________________________
>