[issue40796] dataclasses.make_dataclass: Exception when called with different field orders
New submission from Darrick Yee :
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...
--
messages: 370112
nosy: Darrick Yee
priority: normal
severity: normal
status: open
title: dataclasses.make_dataclass: Exception when called with different field
orders
type: behavior
versions: Python 3.7, Python 3.8
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[issue40796] dataclasses.make_dataclass: Exception when called with different field orders
Change by Darrick Yee : -- stage: -> resolved status: open -> closed ___ Python tracker <https://bugs.python.org/issue40796> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40796] dataclasses.make_dataclass: Exception when called with different field orders
Darrick Yee added the comment: 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. -- ___ Python tracker <https://bugs.python.org/issue40796> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40796] dataclasses.make_dataclass: Exception when called with different field orders
Darrick Yee added the comment: Yes, that makes sense. Thank you! On Wed, May 27, 2020, 1:40 PM Eric V. Smith wrote: > > Eric V. Smith 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 > <https://bugs.python.org/issue40796> > ___ > -- ___ Python tracker <https://bugs.python.org/issue40796> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
