[otabdeveloper2]

> python is very expressive, hence the code base have way less numbers of lines than in C++

This doesn't match reality. In reality, many Python projects have way more lines of code than equivalent C++ projects. Probably because of the 'expressiveness' you cite; you can't really showcase your love of coding and job security though artificial complexity without 'expressive' bells and whistles. (This is the idea that lead to languages like Go, I'm pretty sure.)

That said, C++ is plenty 'expressive' itself.

[BiteCode_dev]

> many Python projects have way more lines of code than equivalent C++ projects.

That is mathematically impossible. Even if the syntaxes were exactly the same (which they are not, python syntax is on average shorter), the low level nature of C++ requires your code to do operations that Python does need to do, such as memory management.

It's like stating the sky is red.

[snovv_crash]

Once you've written sufficient unit tests to prove your code works as well as a C++ equivalent does just by compiling, I don't think Python ends up being more dense though.

I'd also argue that operator overloading etc lets C++ be just as expressive as Python, the libraries just need to be designed with that in mind.

[BiteCode_dev]

> Once you've written sufficient unit tests to prove your code works as well as a C++ equivalent does just by compiling

You mean in the same way C++ dev write tests to prove that all their code has no memory error which you get in Python for free ?

Except:

- tests are way shorter to write in python than in C++

- C++ devs often write zero tests for their code, just like python devs

- python duck typing + REPL means compiler checks are rarely necessary

- if you need to be type checks, you use type hints in python, which even then is still less verbose than c++

> I'd also argue that operator overloading etc lets C++ be just as expressive as Python, the libraries just need to be designed with that in mind.

Ok, let's say you have this json:

    [{
        "name": "Kévin",
        "age": 23,
        "hired": "2005-06-03 02:12:33",
        "emails": ["[e-mail]", "[e-mail]"]
    }, {
    }, {
        "name": "Joël",
        "age": 32,
        "hired": "2003-01-02 12:32:11",
        "emails": ["[e-mail]", "[e-mail]"]
    },
    ... other entries
    ]

It's very simple. Very basic. There is no trick in there: it's standard utf8, well formed, no missing value.

You want to print people details in alphabetical order this way:

    Joël (32) - 02/01/03:
    - [e-mail]
    - [e-mail]
    Kévin (23) - 03/06/05:
    - [e-mail]
    - [e-mail]
    ... other entries

This is a 1rst year of college exercise. Nothing remotely complicated. I'm not choosing some fancy machine learning or data processing stuff for which Python has magic libs. Every language can do that easily.

In Python 3.7, which is already 2 years old, the code would be:

    import json
    import datetime as dt

    with open("agenda.json") as fd:

        agenda = sorted(json.load(fd), key=lambda people: people["name"])

        for people in agenda:

            hired = dt.datetime.fromisoformat(people["hired"])
            print(f'{people["name"]} ({people["age"]}) - {hired:%d/%m/%y}:')

            for email in people["emails"]:
                print(f" - {email}")

The entire script is there. There is no trick. This is not a code golf version of of it; I could make it shorter. It really is standard Python. There is no 3rd party lib either.

It's not specific to Python, you would get this expressiveness with Ruby or Perl.

I don't see in which world you would get that in regular, honest to god, day to day, portable C++.

You have to declare types, many includes, you'll have headers and a main function. You have the memory and references to manage.

It doesn't make C++ a bad language.

It doesn't make python a better language.

The C++ version will take way less RAM than the Python version for example.

It's just the nature of those languages implies that.

[steveklabnik]

For fun, I whipped this up in Rust. I decided to go with an explicit struct to serialize it into, because it makes the error handling easier, and is a bit more idiomatic. I kept unwrap because it's similar to the python semantic of throwing an exception. It's pretty close though!

    use chrono::NaiveDateTime;
    use serde::*;
    use serde_json;
    
    #[derive(Deserialize)]
    struct Person {
        name: String,
        age: u32,
        hired: String,
        emails: Vec<String>,
    }
    
    fn main() {
        let data = std::fs::read_to_string("agenda.json").unwrap();
        let mut people: Vec<Person> = serde_json::from_str(data).unwrap();
    
        people.sort_by(|a, b| b.name.cmp(&a.name));
    
        for person in &people {
            let datetime = NaiveDateTime::parse_from_str(&person.hired, "%Y-%m-%d %H:%M:%S").unwrap();
            println!(
                "{} ({}) - {}",
                person.name,
                person.age,
                datetime.format("%d/%m/%y")
            );
    
            for email in &person.emails {
                println!(" - {}", email);
            }
        }
    }

[steveklabnik]

Apparently you can deserialize the date directly with serde and chrono too! So this could be even shorter.

[BiteCode_dev]

And Rust is very, very expressive and concise for a bare metal language. Serde is a beautiful thing.

[jcelerier]

It's a bit longer in C++ but frankly not by that much :

    #include <iostream>
    #include <sstream>
    #include <fstream>
    #include <iomanip>
    #include <nlohmann/json.hpp>
    #include <range/v3/action/sort.hpp>
    
    int main()
    {
      using namespace nlohmann;
      using namespace ranges;
    
      const json parsed = json::parse(std::ifstream("/tmp/json/test.json"));
    
      std::vector agenda(parsed.begin(), parsed.end());
      sort(agenda, {}, [] (const auto& j) { return j["name"]; });

      for(const auto& people : agenda) try {
        std::tm t{};
        std::istringstream(people["hired"].get<std::string>()) >> std::get_time(&t, "%Y-%m-%d %H:%M:%S");
    
        std::cout << people["name"] << " (" << people["age"] << ") - " << std::put_time(&t, "%d/%m/%y") << ": \n";
        for(const auto& email : people["emails"])
          std::cout << " - " << email << "\n";
      } catch (...) { }
    }

[BiteCode_dev]

This is getting ridiculous.

We went from:

> many Python projects have way more lines of code than equivalent C++ projects

To:

> It's a bit longer in C++ but frankly not by that much

With the proof being literally __twice__ more characters, with one line being more than a 100 characters long.

I understand that C++ doesn't have a native JSON lib, and sorting is a bit out there, but giving 3rd party lib access to Python feels like cheating:

    import pandas as pd
    agenda = pd.read_json("agenda.json", convert_dates=["hired"])
    for _, (name, age, hired, emails) in agenda.sort_values("name").iterrows():
        print(f"{name} ({age}) - {hired:%d/%m/%y}:")
        for email in emails:
            print(f" - {email}")

I mean, I can also create a lib that does the entire script, install it, and just do 'import answernh; answerhn.print_json("agenda.json")'

Now again, this is not so say "Python is better than C++". That's not the point.

If you want to write a game engine, C++ makes sense, verbosity doesn't matter, and you don't want the Python GC to kick in. If you want to iterate on your Saas product API quickly, it's probably not the best choice.

Why pretend otherwise? What the point of stating the sky is red?

[snovv_crash]

To be fair to the C++ version, you need to give as many guarantees from your code as C++ does from compiling. To me, in this case this is mainly the output formatting. Python won't tell you until runtime that you have a malformatted string, so add in some unit tests to make sure your string formatting won't crash, and you'll be at a similar number of lines of code as the C++ or Rust version.

[detaro]

I think it shows quite well that the expressiveness difference is not as a large as many would think.

Also, the difference in tone towards jcelerier compared to steveklabnik seems not warranted here. Both IMHO contributed an educational example. Your response here equally does (or does not) apply to the Rust version, doesn't it?

[SaxonRobber]

It also requires a library outside of the standard.

[rfoo]

Java and Perl does not have json in builtin libs, does it make Java/Perl less useful or less expressive than Python?

[steveklabnik]

To be clear, my solution also included two libraries outside of the standard library. That’s idiomatic for Rust.

[jcelerier]

does that matter ? Python does not even have an ISO standard

[otabdeveloper2]

The original post was about 'projects', not code snippets.

If you've done any serious (large, long, multi-team) projects in a dynamically-typed language, you know how quickly they turn into a big ball of mud where you're spending more time refactoring your refactorings than writing useful code.