How both ignore type check and obey line <80 chars

Question

I have this data type that just groups related data. It should be a struct-like thing, so I opted for a namedtuple.

ConfigOption = namedtuple('ConfigOption', 'one two animal vehicle fairytale')

On the other hand, namedtuple has no defaults, so I reside to a hack proposed in another answer.

ConfigOption.__new__.__defaults__ = (1, 2, "White Horse", "Pumpkin", "Cinderella")

Obviously, this makes the type check fail: error: "Callable[[Type[NT], Any, Any, Any, Any, Any], NT]" has no attribute "__defaults__"

Since I'm well aware this is a hack, I tell the type checker so using an inline comment # type: disable:

ConfigOption.__new__.__defaults__ = (1, 2, "White Horse", "Pumpkin", "Cinderella")  # type: disable

At this time... the line becomes too long. I have no idea how to break this line so that it is syntactically correct and at the same time make the type checker skip it:

# the ignore is on the wrong line
ConfigOption.__new__.__defaults__ = \
    (1, 2, "White Horse", "Pumpkin", "Cinderella")  # type: ignore

# unexpected indentation
ConfigOption.__new__.__defaults__ =  # type: ignore
    (1, 2, "White Horse", "Pumpkin", "Cinderella")

So is there a way to exclude a single line from type checking, or to format this long line, so that both the type check is skipped, and the line length is pep-8 compliant?

Python >= 3.7 has defaults for namedtuples. https://docs.python.org/3/library/collections.html#collections.namedtuple — Sebastian Loehner, Mar 27 '19 at 11:19

score 2 · Accepted Answer · answered Mar 27 '19 at 11:24

2

what's wrong with:

option_defaults = (1, 2, "White Horse", "Pumpkin", "Cinderella")
ConfigOption.__new__.__defaults__ = option_defaults  # type: ignore

answered Mar 27 '19 at 11:24

Sebastian Loehner

1,302
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5

1

apart from pep-8 telling me to use OPTION_DEFAULTS, nothing. Thanks! – xtofl Mar 27 '19 at 13:22

score 0 · Answer 2 · answered Mar 27 '19 at 11:35

Enum seems to follow the constraints you require, and is quite concise.

You can use the Functional API, which itself says the semantics resemble namedtuple

>>> from enum import Enum
>>> Enum('ConfigOption', 'one two animal vehicle fairytale')
<enum 'ConfigOption'>
>>> ConfigOption = Enum('ConfigOption', 'one two animal vehicle fairytale')
>>> [c for c in ConfigOption]
[<ConfigOption.one: 1>, <ConfigOption.two: 2>, <ConfigOption.animal: 3>, <ConfigOption.vehicle: 4>, <ConfigOption.fairytale: 5>]

How both ignore type check and obey line <80 chars

2 Answers2