Create new Session method prepare_redirected_request.

[zackw]

This is almost entirely moving code around: the new method is
most of the code that used to be the loop body of resolve_redirects.

[Lukasa]

Why are we removing the redirect mixin?

[zackw]

It becomes obvious when you break up resolve_redirects this way that both halves rely on internal Session data and therefore ought to be Session methods.

TBH I don't really understand why the mixin existed in the first place - it's not providing a useful conceptual division nor could it realistically have been applied to any other class but Session.

[zackw]

(To be scrupulously accurate: the remaining use of internal Session data inside resolve_redirects is unnecessary - it duplicates something send does already. I was keeping this pull strictly to code motion so I left it there. Even so, though, the conceptual argument stands.)

[sigmavirus24]

TBH I don't really understand why the mixin existed in the first place

Testability (as was shown with #1963). Frankly, other parts of a Session would be easier to test if they were mix-ins as well (specifically the cookie handling pieces of logic). Then again, most people don't care how testable their code is.

nor could it realistically have been applied to any other class but Session

That's not exactly right. Most people would not have wanted to apply it to any other class but Session, but it very realistically could have been applied to any other class that was carefully constructed (again, shown in #1963).

[Lukasa]

I also disagree with your argument that it doesn't provide a good conceptual division, and I think this change emphasises the conceptual division, not weakens it. Redirection is complicated, and the number of methods that handle redirection is increasing all the time. The mixin provides an organisational framework for that code which makes the code easier to follow (IMO). The fact that you've added more methods here makes that even clearer.

Yes, the mixin is tightly coupled to the Session class, but that's ok: it's an organisational and conceptual distinction not a philosophical one.

[kennethreitz]

Exactly what @Lukasa said — the Mixin is all about readability :)

[kennethreitz]

Closing due to inactivity.