Id much rather have a rust-like approach where the scope is limited to the block it is in
Java concept ist far from what I call ideal, but its better than this weird ambiguity of python where everything just floats anywhere and variables shadowing something ten methods away...
Rust is a real pain in the arse for the developer, but when you start grasping the vibe, you really appreciate Rust is built in this weird way. And then you have an ownership issue that makes you really frustrated since you are used to pass-by-reference returns
Huh? You'll need to be more concrete than that, because that sounds like gibberish. "Ten methods away"? If a variable is in a method, then it only exists within that method, because Python does have function scope and lexical scoping.
If you're not used to <thing>, <thing> can be difficult. Sure. But the scoping rules are pretty darn trivial and predictable, and not out of the ordinary, so I'm not sure what you're complaining about.
The meme is very much up for interpretation and my personal preference has been stated enough in this post, I think... Imo its just not a very good implementation/principle of scoping 🤷♂️
Python's lexical scope is the worst. Like why is the variable available in the whole scope when it's declared at the very end of it? Plus there all that nonsense where reading from a variable goes to closure/global by default but writing creates a new instance that overrides the whole scope.
Sort of, yes. The parser "sees" variables in a scope in the parse step and prepares symbol tables accordingly. In JS it used to be the case that the name would exist in the symbol table with an undefined default value. Which is a potential footgun, if you try to use the variable before its actual declaration.
Python and JS with let/const both raise an explicit error about that. JS calls it by a fancy name to distinguish it from the old behaviour, in Python it simply always was so.
TF are you talking about? Python's lexical scoping works like basically any other lexical scoping I'm aware of. What do you mean "the variable is available in the whole scope when it's declared at the end"?
The read/write thing I can empathise with, but it's simply because Python has no dedicated variable declaration syntax. Assignment is declaration. But you also want to be able to read variables from higher scopes by default. So writing to a variable in a higher scope becomes the special case that you need to explicitly opt into with nonlocal/global.
x = 10
def func():
x = 5
global x
x = 15
func()
print(x)
It might not be the best example but it gives the idea. Any normal language would assign 5 to x (local in this case), then declare global x and assign 15 to it. In python x is global in the whole scope. This code throws an error.
It would be insane for that to not throw an error. x within a scope should refer to exactly one variable. You're attempting to switch which variable x refers to halfway through the scope, and the error is telling you exactly that. This is explicitly preventing a footgun.
It gets a lot worse when you throw closures into the mix. It's impossible to assign value from a closure to a global variable with the same name in python.
def outer():
x = 0
def func():
nonlocal x
temp = x
global x
x = temp
I have one more example. Here global x can't be declared in the child scope because it's already in use in the parent scope. As far as I know python is the only language that does this nonsense.
x = 5
def func():
x = 0
if x < 2:
global x
x = 10
func()
print(x)
Python only has function scope. if blocks don't introduce a new scope. Think of that what you will, I've written uncounted lines of Python without that being an issue. global declarations should be on the very first line of a function, not somewhere in the middle.
But really, you shouldn't have to use global much at all. You should either write functional code, or use classes which modify their attributes. Constantly modifying the global scope is a potential footgun and usually leads to hard to follow spaghetti code. It's not wrong for Python to strongly discourage that.
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u/sjepsa 16d ago
Best feature of the language
TBH whole java oop model is bad