Python 3.7

  • Python 3.7 released: Standard checklist:
    • Run installer
    • Delete the old 3.6 folder from /Applications
    • Run the certificate command in the new 3.7 folder (the other shits a PATH into my shell profile, don't need it)
    • Run IDLE and verify it's 3.7.0. Happily, no longer have to fight with updating Tcl/Tk.
    • Run "python3" from Terminal and verify it's 3.7.0
    • Run a random Python script to make sure nothing's broken.

Nanosecond-accurate time functions and switching more ASCII/C Locale into UTF-8 are nice improvements, but those are more patching up legacy annoyances than "must have".

I'm mostly interested in dataclasses, which makes it much easier to build little struct-type objects instead of random dicts or lists which have all sorts of problems (no equality, hashing, typo-safety).

I greatly dislike the addition of BDSM typing, but it's mostly optional, EXCEPT you have to use them in dataclasses:

from dataclasses import dataclass
@dataclass
class Point:
    x : float = 0.0
    y : float = 0.0

>>> p = Point()
>>> p
Point(x=0.0, y=0.0)
>>> q = Point(1.1, 2.2)
>>> q
Point(x=1.1, y=2.2)

If I define Point without the type annoytations[my new favorite typo!], only the default constructor works, and it doesn't print the fields as a string.

@dataclass
class Pointless:
    x = 0.0
    y = 0.0

>>> f = Pointless()
>>> f
Pointless()
>>> f.x
0.0
>>> f.y
0.0

Real examples might be a lot more complex than a point, and by then the cost of building a proper class with __init__ and everything yourself isn't such a big deal, so I can see dataclasses mostly being used for very simple struct-like containers.

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