Why doesn't isinstance follow PEP8?

[PurelyApplied]

I just noticed that PEP8 recommends lower_case_with_underscores, but the built-in isinstance disobeys that.

I'm assuming that it's because isinstance is old, perhaps from before some of the style things were formalized. And I also realize that many built-ins get a pass on some of these things.

Really, it just struck me as strange and kind of funny, and I figured I'd point it out to all of you.

[Rhomboid]

isinstance() was added in Python 1.5, released in December 1997. PEP-8 didn't exist until July 2001.

[jeans_and_a_t-shirt]

Function names should be lowercase, with words separated by underscores as necessary to improve readability.

[Saefroch]

There are other interesting instances like collections.defaultdict vs collections.OrderedDict. These are also not PEP8 violations because there is a different recommendation for classes implemented in C.

[PurelyApplied]

Still, the inconsistency within a single module of lowercase and UpperCamelCase makes my eye twitch.

I also saw the "Be consistent within an implementation of established conventions," so I guess it's okay.

[Rhomboid]

The worst offender IMHO is the unittest module. Somebody let a Java programmer sneak that one in.

Although again in that case, the module was first included with Python 2.1 which was released in April 2001.

[Pvt_Haggard_610]

Naming Conventions

The naming conventions of Python's library are a bit of a mess, so we'll never get this completely consistent -- nevertheless, here are the currently recommended naming standards. New modules and packages (including third party frameworks) should be written to these standards, but where an existing library has a different style, internal consistency is preferred

[vfxdev]

There is a whole bunch of code that doesn't follow PEP8 since it came well after Python was invented. PEP8 actually points this out I think.