17.1.0 breaks passing default to Attribute by keyword

[exarkun]

txaws has some code that constructs Attribute directly (it is public, after all). It does so by passing a value for the default parameter by keyword (it is public, after all).

https://github.com/twisted/txaws/blob/8127b45978aa7b91e65eae15546a63440932b57f/txaws/client/_validators.py#L46-L54

This worked prior to 17.1.0 but no longer does.

[Tinche]

Hm, I think this can be reverted.

[Tinche]

I pushed a fix for this into #193.

[hynek]

In our defense, the docs excplitly says you should never instantiate it yourself. :-|

But yeah we'll fix it.

[exarkun]

Please don't make me read a big pile of docs just to find out that x.Y in your package isn't actually public even though it follows the public naming convention. :/ If I did that I wouldn't have any time left in my life to do any other things.

[hynek]

Serious question: how do you designate something to be public to read/inspect but private to create/write in an other way than docs?

[exarkun]

Make the constructor private. So, for example, have IAttribute (self-evidently public) telling people what they can read from a thing and have an _Attribute (self-evidently private) type that implements it.

[hynek]

fixed in #193