[nayuki]

Java made opaque types possible from the very start by private and package-private constructors.

It's sad to see that many features regarding object-oriented programming and static typing are implemented worse in Python than Java. Various examples: __str__() vs. toString(); underscore vs. private; @staticmethod/@classmethod vs. static; generic types are so clunky in Python; types are not shown in the official Python standand library documentation; __init__() doesn't force you to call super() whereas it's mandatory in Java; @override (Python 3.12; year 2023) copying Java @Override (JDK 1.5; year 2004) very late; convention changing from duck typing (always available in Python) to structural typing (optional in Python, mandatory in Java).

[zephyrthenoble]

I agree that these are implemented "worse" than Java but that's because Python wants these things to be optional! You can complain about it as much as you want but that just means it's the wrong language for you, if that's important to you.

[nayuki]

(I'd like to note that I wrote a lot of code in Java and Python, and continue to use each language in its respective strong areas. This isn't meant as a drive-by attack of "Java r00lz, Python sux"; this is an experienced take.)

My real problem with the evolution of Python is that initially, the language and the community was positioned as anti-Java, anti-big-OOP-like-C++, and then it changed into the thing that it was against, but in a roundabout and suboptimal way. To me, the initial vibe of Python was, "write a 100-line script, don't worry about explicitly documenting types, don't worry about grand architecture, don't worry about creating custom classes, don't worry about encapsulation and public/private". I've been with Python since year 2007 in the 2.x days, and Java since 2002.

Initial examples: Why go through the ceremony of `public static void main(String[] args)` when Python just executes the script line by line at the top level? Oh wait, now you have things like `import` actually executing code instead of simply being a compile-time namespace convenience, and you need weird techniques like `if __name__ == "__main__"`. Why `System.out.println()` when `print()` is so much more concise? But now you're polluting the global namespace, and `print(file=sys.stderr)` isn't that elegant either.

Static typing in Python is the biggest hypocrisy ever. As I understood it, Python scripts were meant to be lightweight and free of the tyranny of enterprise OOP which was epitomized by Java. But people found out that keeping track of types in your head is laborious and error-prone, and getting a compiler to check {that the shape of your objects and function calls match} is a huge productivity boost. And so Python 3 enabled static type hints... which, like I said before, Java had from day zero. To make matters worse, static type hint features were introduced progressively over the years, leading to things getting deprecated from the `typing` module and moved to things like `T|None` and `list[T]` and `collections.abc`.

IIRC the old practice in Python was that you specified some kind of interface in prose or in code (e.g. `class IoStream: def read(); def close()`), but you didn't need to explicitly use that interface as a superclass; you can just duck-type your way around things. But this completely goes against static typing, so I'm pretty sure the new preferred way is to explicitly use abstract superclasses... just like Java did all along (and is mandatory).

I really don't think having top-level (module) variables and functions in Python is a good thing, especially because then they are duplicated as fields and methods in classes. In Java, fields and methods (whether static or instance) can only be placed in classes, and I think this particular straitjacket is a good thing.

> because Python wants these things to be optional

We can both agree that Python gives multiple ways to do things (e.g. no static type hints vs. static type hints). This flies in the face of:

> Readability counts.

> The Zen of Python / There should be one-- and preferably only one --obvious way to do it. -- https://peps.python.org/pep-0020/

Probably the most tragic example is the ways to build up strings in Python: `+` and str(), `%` operator, `str.format()`, f-string.

(To be fair, I have a laundry list of complaints about Java too, such as: .class files and the JVM being an intermediate layer that needs to be understood which is actually different from the Java source language, lack of in-place structs so `new Point[]` is very painful on the memory system, awkward string interpolation/formatting compared to Python's f-strings, very awkward JDBC compared to for example Python sqlite3 API, kinda clunky for web server programming, very awkward JSON handling, enterprisey libraries and APIs that are perfectly documented but are impossible to actually understand.)

[anon7725]

> so I'm pretty sure the new preferred way is to explicitly use abstract superclasses... just like Java did all along (and is mandatory).

typing.Protocol is a good fit for this use case

  from typing import Protocol
  
  class HasMessage(Protocol):
      def get_message(self) -> str: ...
  
  class A:
      """Implicit (duck-typed)"""
      def get_message(self) -> str:
          return "A"
  
  class B(HasMessage):
      """Explicit"""
      def get_message(self) -> str:
          return "B"
  
  class C:
      def get_message(self) -> int:
          return 1
  
  def print_message(m: HasMessage) -> None:
      print(m.get_message())
  
  print_message(A())
  print_message(B())
  print_message(C())  # fails type check

[alanwreath]

Are you ever supposed to inherit from the protocol though(unless you’re defining another protocol)? One of the great things about protocols is that your class doesn’t even have to know about the protocol explicitly. What this code looks closer to doing (style wise) is an abstract base class

[anon7725]

"To explicitly declare that a certain class implements a given protocol, it can be used as a regular base class. In this case a class could use default implementations of protocol members. Static analysis tools are expected to automatically detect that a class implements a given protocol. So while it’s possible to subclass a protocol explicitly, it’s not necessary to do so for the sake of type-checking."

https://peps.python.org/pep-0544/#explicitly-declaring-imple...

[formerly_proven]

> My real problem with the evolution of Python is that initially, the language and the community was positioned as anti-Java, anti-big-OOP-like-C++, and then it changed into the thing that it was against, but in a roundabout and suboptimal way. To me, the initial vibe of Python was, "write a 100-line script, don't worry about explicitly documenting types, don't worry about grand architecture, don't worry about creating custom classes, don't worry about encapsulation and public/private". I've been with Python since year 2007 in the 2.x days, and Java since 2002.

It really wasn't that anti-Java. Late 90s / early 2000s had a huge branch that was very dedicated to Java-style OOP. E.g. anything to do with Zope, and GvR himself worked on that at the time. Zope even has had its own ABC / interface system, specifically modeled after Java interfaces. stdlib logging is a reimplementation of log4j in Python and so on.

[david422]

> Static typing in Python is the biggest hypocrisy ever

Yes, agreed. I used to work on a large python codebase and tried to add type hints where I could. The issue is that python was not the right tool for the job - except that switching to the right tool was a non-starter. So type hints were the best I could do.

[prerok]

It is indeed a significant undertaking. But... it is doable. I've worked on a code base that converted several functionalities to golang. It did take a lot of effort and quite a lot of planning.

[alanwreath]

Let it out co-internet programmer. It’s ok. The pain is real. We both love and hate our languages. It’s natural and healthy.

[kokada]

> Why go through the ceremony of `public static void main(String[] args)` when Python just executes the script line by line at the top level? Oh wait, now you have things like `import` actually executing code instead of simply being a compile-time namespace convenience, and you need weird techniques like `if __name__ == "__main__"`.

I don't think this is a fair criticism. Python is a scripting language, it makes sense that the code is executed line by line at the top level. This is also how other programming languages from its time like Perl or Bash does it. Even newer scripting languages like Ruby does something similar.

> Why `System.out.println()` when `print()` is so much more concise? But now you're polluting the global namespace, and `print(file=sys.stderr)` isn't that elegant either.

Another criticism that I don't think it is fair. Lots of other languages "polutes" the global namespace. I actually can't think another language other than Java that doesn't. Python at least still allow you to manually `import builtins`, but Go for example AFAIK has no mechanism for you to reference builtins if you end up shadowing them.

Also I find `print(file=sys.stderr)` pretty much elegant, it works exactly how I would expect, it also means I can open a file and write to it using `print`.

> And so Python 3 enabled static type hints... which, like I said before, Java had from day zero.

Again, I don't think this is fair. I find Python 3 type-hints much more powerful than whatever type system Java has, especially because Python has Option types that actually make the type system useful (Java is infamous for its NullPointerException for a reason).

[lmm]

> Why go through the ceremony of `public static void main(String[] args)` when Python just executes the script line by line at the top level? Oh wait, now you have things like `import` actually executing code instead of simply being a compile-time namespace convenience, and you need weird techniques like `if __name__ == "__main__"`.

You'll note that even Java now recognises that "public static void main(String[] args)" was pointless ceremony.

> Python scripts were meant to be lightweight and free of the tyranny of enterprise OOP which was epitomized by Java. But people found out that keeping track of types in your head is laborious and error-prone, and getting a compiler to check {that the shape of your objects and function calls match} is a huge productivity boost. And so Python 3 enabled static type hints... which, like I said before, Java had from day zero.

Java didn't have "hints", it had mandatory types everywhere. Which, again, they've now recognised was a bad idea and gradually removed. Having a type system is a good idea, and maybe if Python had taken more inspiration from OCaml (or more people had used OCaml instead of either Java or Python) we'd all be better off, but the early-2000s-Java cure of mandatory types everywhere was worse than the disease.

> To make matters worse, static type hint features were introduced progressively over the years, leading to things getting deprecated from the `typing` module and moved to things like `T|None` and `list[T]` and `collections.abc`.

Which happens in any language that evolves over time. Java, despite having a type system built into the language from day 1, now has about ten different deprecated sets of nullness annotations with overlapping functionality.

> I really don't think having top-level (module) variables and functions in Python is a good thing, especially because then they are duplicated as fields and methods in classes. In Java, fields and methods (whether static or instance) can only be placed in classes, and I think this particular straitjacket is a good thing.

Nah. No other language has adopted Java's approach, for good reason. Functions and values are easier than classes and the language shouldn't force you to complicate your code when there's no need to.

> Probably the most tragic example is the ways to build up strings in Python: `+` and str(), `%` operator, `str.format()`, f-string.

It sucks, but what's the alternative? Either a language dies young or it lives long enough to have a bunch of deprecated crap in it.

[strbean]

> You'll note that even Java now recognises that "public static void main(String[] args)" was pointless ceremony.

There is still the part of the ceremony that actually mattered: having a single entrypoint instead of the option to litter side effects throughout the file and having those side effects execute automatically on import.

> It sucks, but what's the alternative?

3.0 was a big missed opportunity to kill a lot of the deprecated cruft.

[lmm]

> the option to litter side effects throughout the file and having those side effects execute automatically on import.

You can actually do that in Java too with static initialisation blocks.

> 3.0 was a big missed opportunity to kill a lot of the deprecated cruft.

Maybe. 3.0 already came damn close to killing the language. If they'd made the changes any more radical it could easily have been another Perl 6.

[causal]

Python is much older than Java, and Java is a big OO-first language. It's a bit like saying Python doesn't do functional as well as Erlang.

[qrobit]

Much older? Wikipedia says[^1][^2] java appeared in 1995 (started in 1991), while python appeared in 1991 (started in late 1980s). 4 years doesn't seem too far apart, considering both language are >30 years old now.

[^1]: https://en.wikipedia.org/wiki/Python_(programming_language)

[^2]: https://en.wikipedia.org/wiki/Java_(programming_language)

[nayuki]

Not only that, but Python had the benefit of doing a very painful break in version 3 (2008), when they had the option to cleaned up almost anything they wanted.

(Some changes in Python 3 I can recall: bytes/str/unicode being the biggest one; fixing mutable variables in nested functions; changing some obscure behavior in class hierarchies and overload resolution; changing things like range() and map() to lazy evaluation.)

For better or for worse, Java has maintained very good (not perfect) compatibility throughout, even with painful changes like generics in 1.5, lambdas in 8, modules in 9, eventual removal of applets and SecurityManager, etc. This also contrasts with C#/.NET, which I think had some breaking changes over the decades.