What's New in Python 3.12

Post by wodenokoto » Thu, Oct 19, 2023, 6:28 AM UTC

ddejohn wrote: post #101

wodenokoto wrote: post #56

Earlier quoted context omitted.

def safe_navigation(obj, path: List[str], default=None): try: for key in path: obj = obj[key] return obj except KeyError: return default Yeah. I thought it would just be a try-except, but that turned out pretty ugly. But really, how do you know if your path is missing or the object at the end of the path is None, without using exceptions for communicating this?

There's certainly humor in a function called "safe navigation" mutating the data structure I'm supposedly safely navigating through :D

Post by klibertp » Thu, Oct 19, 2023, 7:33 AM UTC

BoumTAC wrote: post #79

klibertp wrote: post #76

Earlier quoted context omitted.

You can't confuse keys in a hash table with properties of objects. It's not confusing, it's a useful distinction. Most languages that have both objects and associative arrays (so not Lua or JavaScript) make this distinction. It's not particularly error prone. You're simply refusing ("don't care why") to learn how to use the tool you're given.

user dictionnary => user["email"] user instance from a django model => user.email It is error prone. You're simply refusing to see an aberration. That's how the language works, but it doesn't mean it's intuitive and easy to understand especially for a language known for being easy to use and understand.

Post by wodenokoto » Thu, Oct 19, 2023, 8:35 AM UTC

ddejohn wrote: post #101

wodenokoto wrote: post #56

Earlier quoted context omitted.

def safe_navigation(obj, path: List[str], default=None): try: for key in path: obj = obj[key] return obj except KeyError: return default Yeah. I thought it would just be a try-except, but that turned out pretty ugly. But really, how do you know if your path is missing or the object at the end of the path is None, without using exceptions for communicating this?

There's certainly humor in a function called "safe navigation" mutating the data structure I'm supposedly safely navigating through :D

    $ python3
    Python 3.11.6 (main, Oct  2 2023, 20:46:14) [Clang 14.0.3 (clang-1403.0.22.14.1)] on darwin
    Type "help", "copyright", "credits" or "license" for more information.
    >>> from typing import List
    >>> def safe_navigation(obj, path: List[str], default=None):
    ...     try:
    ...         for key in path:
    ...             obj = obj[key]
    ...         return obj
    ...     except KeyError:
    ...         return default 
    ... 
    >>> obj = {1: {1: {1: 2}}}
    >>> safe_navigation(obj, [1,1,1])
    2
    >>> obj
    {1: {1: {1: 2}}}

Post by chrismorgan » Thu, Oct 19, 2023, 12:58 PM UTC

flakes wrote: post #25

https://docs.python.org/3/whatsnew/3.12.html#whatsnew312-pep... "PEP 692: Using TypedDict for more precise *kwargs typing" seems pretty great. That'll be really helpful for nested method calls which proxy a lot of their arguments along. I can also see that helping out when creating stub libraries.

Post by ddejohn » Thu, Oct 19, 2023, 9:14 PM UTC

dmr_92 wrote: post #107

ddejohn wrote: post #101

Earlier quoted context omitted.

There's certainly humor in a function called "safe navigation" mutating the data structure I'm supposedly safely navigating through :D

I don't think this is correct . The name obj gets rebound, but the dictionary being traversed isn't mutated in any way.