Comment by zak_mc_kracken | Hacker News Reader

Comment by zak_mc_kracken | Hacker News Reader

Parent Full thread

> it’s sometimes asked why len in Python is a function, rather than a method. The answer is that of course it is a method, called __len__. The real answer is that Python pointedly and deliberately does not reserve any method

That's some comical post rationalization.

The reason why len is a function is because it was in Python before Python started receiving OO features.

As a result, Python is a crazy hodge podge of imperative, OO and functional semantics where you never know if you should be calling `o.foo()` or `foo(o)` unless you've been writing Python since the late 90s.

This is a myth. Python supported classes close to the start of its existence, way before it became popular.

If you have some evidence to back that up then you'll want to correct http://en.wikipedia.org/wiki/History_of_Python

"In February 1991, Van Rossum published the code (labeled version 0.9.0) to alt.sources. Already present at this stage in development were classes with inheritance, exception handling, functions [...]"

I really like the approach of allowing either kind of call, with the "dot" style mere convenience over the function style. Rust has that sort of thing:

    let v = &vec![1u32,2,3];
    println!("{}", v.len());
    println!("{}", Vec::len(v));

In general this feature is sometimes called "Universal Function Call Syntax" (UFCS), though interestingly Rust does it exactly the opposite of most other languages with this feature. In Rust, defining a method lets you use it as a free function; in C# and D, defining a free function lets you use it as a method.

I always thought this was a weird nod to typeclasses

Reply on news.ycombinator.com