4 ms·

Not just for beginners, the proposed syntax looks horrible in general. It's moreover already possible to put this into one line: libpaths = [] if libpaths is

by catdog 8y ago

Not just for beginners, the proposed syntax looks horrible in general. It's moreover already possible to put this into one line: libpaths = [] if libpaths is None else libpaths.split(":")

gaius 8y ago
Yes, this PEP looks like it is trying to turn Python into Ruby where the ? suffix is common for a function that returns a bool. Also weird syntactic magic that you can't really figure out, you have to be told about. I wonder if the original author of the PEP is a "rubyist". Of course in Python [] is False and in Ruby it's true...
- hnra 8y ago
  Looks exactly like adding the ?? [1] and ?. [2] operators from C#. [1]: https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-coalescing-operator https://docs.microsoft.com/en-us/dotnet/csharp/language-refe... [2]: https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-conditional-operators https://docs.microsoft.com/en-us/dotnet/csharp/language-refe...
  - gaius 8y ago
    operators from C# Why not go the whole hog then, and do a Option[1] ;-) [1] https://en.wikipedia.org/wiki/Option_type#F# https://en.wikipedia.org/wiki/Option_type#F#
    - mmirate 8y ago
      Option is bubkes if the language itself still has the billion-dollar mistake; that's why F# and Scala are far less practical than OCaml. Python also has it with "None" (though since it is dynamically typed, it's arguable that from the perspective of any given type, every value of every other type is a fresh instance of the billion-dollar mistake). And sadly, removing None from Python and replacing it by Option - let alone removing Exception and letting Result (aka Either) take its rightful place - would cause huge amount of Python code to need rewriting. And it wouldn't even be worth it because of dynamic typing.
    - marcosdumay 8y ago
      What does you gain from optionals if you can't determine types at compile time?
      - dragonwriter 8y ago
        > What does you gain from optionals if you can't determine types at compile time? As well as type checking (which is relevant because Python has AOT checkers even if they are optional), Options, compared to bills, give you nestability, which is a runtime advantage not dependent on static type checking.
- dragonwriter 8y ago
  > Yes, this PEP looks like it is trying to turn Python into Ruby where the ? suffix is common for a function that returns a bool. No, it's nothing like the Ruby convention. It's much more like th C# operators.
agumonkey 8y ago
do people use x = x or [] or is it considered non idiomatic in python ?
- tomchristie 8y ago
  It’s okay-ish. You do need to be careful about what falsey values `x` might be tho, as it could introduce edge-case bugs. Using `x = [] if x is None else x` is more precise.
  - Asooka 8y ago
    I would really just write `if x is None: x = []`

by catdog 8y ago

Not just for beginners, the proposed syntax looks horrible in general. It's moreover already possible to put this into one line: libpaths = [] if libpaths is None else libpaths.split(":")

gaius 8y ago

Yes, this PEP looks like it is trying to turn Python into Ruby where the ? suffix is common for a function that returns a bool. Also weird syntactic magic that you can't really figure out, you have to be told about. I wonder if the original author of the PEP is a "rubyist". Of course in Python [] is False and in Ruby it's true...

hnra 8y ago
Looks exactly like adding the ?? [1] and ?. [2] operators from C#. [1]: https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-coalescing-operator https://docs.microsoft.com/en-us/dotnet/csharp/language-refe... [2]: https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-conditional-operators https://docs.microsoft.com/en-us/dotnet/csharp/language-refe...
- gaius 8y ago
  operators from C# Why not go the whole hog then, and do a Option[1] ;-) [1] https://en.wikipedia.org/wiki/Option_type#F# https://en.wikipedia.org/wiki/Option_type#F#
  - mmirate 8y ago
    Option is bubkes if the language itself still has the billion-dollar mistake; that's why F# and Scala are far less practical than OCaml. Python also has it with "None" (though since it is dynamically typed, it's arguable that from the perspective of any given type, every value of every other type is a fresh instance of the billion-dollar mistake). And sadly, removing None from Python and replacing it by Option - let alone removing Exception and letting Result (aka Either) take its rightful place - would cause huge amount of Python code to need rewriting. And it wouldn't even be worth it because of dynamic typing.
  - marcosdumay 8y ago
    What does you gain from optionals if you can't determine types at compile time?
    - dragonwriter 8y ago
      > What does you gain from optionals if you can't determine types at compile time? As well as type checking (which is relevant because Python has AOT checkers even if they are optional), Options, compared to bills, give you nestability, which is a runtime advantage not dependent on static type checking.
dragonwriter 8y ago
> Yes, this PEP looks like it is trying to turn Python into Ruby where the ? suffix is common for a function that returns a bool. No, it's nothing like the Ruby convention. It's much more like th C# operators.

agumonkey 8y ago

do people use x = x or [] or is it considered non idiomatic in python ?

tomchristie 8y ago
It’s okay-ish. You do need to be careful about what falsey values `x` might be tho, as it could introduce edge-case bugs. Using `x = [] if x is None else x` is more precise.
- Asooka 8y ago
  I would really just write `if x is None: x = []`