It makes perfect sense actually. I did write another comment here if you are interested.

This is how operator overloads were written going back to the initial version of C++ back in 1985. The only new thing is that we can now add = default to get the compiler to generate a default implementation that compares all the member variables for you.

Maybe to a non C++ dev, but a lot of C++ is probably incomprehensible to a non C++ dev, just like there are other laguages that are incomprehensible to C++ devs. To me it makes perfect sense as it works just like all the other operator overloads.

auto - let the compiler deduce return type

operator<=> - override the spaceship operator (pretty sure it exists in python too)

(const ClassName&) - compare this class, presumably defined in Class name, with a const reference of type Class name, i.e. its own type.

const - comparison can be made for const objects

= default; - Use the default implementation, which is comparing all the member variables.

An alternate more explicit version, which is actually what people recommend:

auto operator<=>(const ClassName&, const ClassName&) = default;

if I just want to have less than comparison for example I would:

This one makes it explicit that you’re comparing two Class name objects.

if I just want to have less than comparison for example I would:

auto operator<(const ClassName&, const ClassName&) = default;

If I need to compare against another class I could define: auto operator<(const ClassName&, const OtherClass&)

You mean copy/move constructor and assignment operator?

Unless you have any special handling the ones generated by the compiler automatically should work just fine. But if you do have to define them for some reason (which is becoming increasingly rare) you would need to define both if you need both copy/move construction and copy/move assignment.

I do appreciate how newer C++ standards have made these kinds of things a lot easier too.

Define all comparison operators with just one one line using C++20

auto operator<=>(const ClassName&) const = default;