this post was submitted on 29 Dec 2024

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I love new features (lemmy.zip)

submitted 1 week ago by [email protected] to c/[email protected]

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[–] [email protected] 1 points 2 days ago

Violates the Law of Demeter

[–] [email protected] 80 points 6 days ago

I'm not sure if this is serious or not and that scares me.

[–] [email protected] 19 points 6 days ago (3 children)

I honestly don't know why they even have -> instead of just a dot like everyone else. The compiler knows whether it's a record, object, pointer, or any level of pointer to pointers.

Why make the programmer do the donkey work?

[–] [email protected] 1 points 11 hours ago

Operator overloading allows you to redefine what each operator does. It's essential to achieve a truly fucked up code base

[–] [email protected] 11 points 6 days ago

It's important for objects that can be dereferenced. Smart pointers have methods that can be accessed with dot syntax like swap(). You can still dereference through a smart pointer using arrow syntax to access methods on the referenced type since they overload the operator->() method.

[–] skulbuny 2 points 6 days ago

I love the arrow in functional programming. Some functional languages (like reasonml) has multiple arrow operators that did different things like this one -> would put the argument in the first position (a popular JS pattern) and the big arrow |> would put it last like most functional languages.

I know this is about CPP but honestly I love the way it looks, but I'm a weirdo lol

[–] [email protected] 14 points 6 days ago

Please don't give them ideas

[–] [email protected] 14 points 6 days ago (1 children)

I pray for this to be real because it's the perfect syntactic sugar for C++. The kind that you'd think makes sense if you didn't have to write C++ for anything more complex than a high school project.

[–] mindbleach 4 points 6 days ago

Right? Every C++ feature needs to be lightly cursed.

[–] [email protected] 92 points 1 week ago (2 children)

the :================D operator

[–] [email protected] 7 points 6 days ago

New language idea:

:====D
:==========D 0
:=======0==D~~~
:==========D ~0

[–] sunoc 22 points 1 week ago

Ebin :D

[–] [email protected] 18 points 1 week ago (1 children)

C++26: remove C++

[–] WhyJiffie 4 points 5 days ago (1 children)

C++26: The Rust Book

[–] [email protected] 1 points 5 days ago

I really hope so but they first need a language specification. Without that it's no use for me.

[–] [email protected] 12 points 1 week ago

TIHI

[–] [email protected] 8 points 1 week ago

C++ is a joke.

[+] [email protected] -8 points 1 week ago (7 children)

Why do you even have pointers to pointers?

[–] [email protected] 20 points 6 days ago* (last edited 6 days ago) (1 children)

Mostly because at the lowest level of computing (machine code and CPU instructions), pointers are the only method (that I know of) of any kind of indirection.

At the lowest level, there are 2 types of references:

CPU registers
memory addresses (pointers)

Every higher level language feature for memory management (references, objects, safe pointers, garbage collection, etc) is just an abstraction over raw pointers

Pointers themselves are really just abstractions over raw integers, whose sole purpose is to index into RAM

With that in mind, pointers to pointers are a natural consequence of any kind of nested object hierarchy (linked lists, trees, objects with references to other objects, etc)

The only other kind of indirection would be self-modifying machine code (like a Wheeler Jump). But the computing world at large has nixed that idea for a multitude of reasons

[+] [email protected] -6 points 6 days ago (1 children)

linked lists, trees, objects with references to other objects

That’s not a pointer to another pointer, but a pointer to a data structure that happens to contain another pointer.

[–] [email protected] 15 points 6 days ago* (last edited 6 days ago) (2 children)

The distinction is meaningless in the land of Opcode's and memory addresses

For example, a struct is just an imaginary "overlay" on top of a contiguous section of memory

Say you have a struct

struct Thing {
  int a;
  int b;
  Thing* child;
}

Thing foo {}

You could easily get a reference to foo->child->b by doing pointer arithmetic

*((*((*foo) + size(int)*2)) +size(int))

(I've not used C much so I've probably got the syntax wrong)

[–] [email protected] 1 points 6 days ago (1 children)

Yes, you can do crazy shit if you try hard enough, but every reasonable programmer would access foo->child->b als foo->child->b and not via that crazy LISPy expression.

By question was: Why would you have a pointer to a memory address that itself only holds a pointer somewhere else?

So far the only reasonable explanation is from @[email protected]:

arrays of function pointers

pass by reference of a pointer

[–] [email protected] 1 points 5 days ago

I'm more talking about theory than practical.

I've not developed anything in C/C++, so I don't know practical uses for a double pointer, aside from multidimensional arrays, or arrays of pointers

My point was that, conceptually, pointers to pointers is how most complex data structures work. Even if the C representation of said code doesn't have a int** somewhere

[–] [email protected] 1 points 6 days ago

Magic.

Blasphemy.

[–] [email protected] 14 points 6 days ago

Pointers just point to memory addresses, and because pointers are stored in memory addresses, it just kind of naturally falls out that way.

[–] [email protected] 4 points 6 days ago

Because int main(int argc, char** argv)

[–] mindbleach 2 points 6 days ago (1 children)

Because pointers are real.

[–] [email protected] 1 points 6 days ago (1 children)

That’s the best thing I’ve read in a while, and I’m only on page 2!

[–] mindbleach 2 points 6 days ago (1 children)

James Mickens does good work.

[–] [email protected] 2 points 6 days ago

If the Mossad wants your data, they’re going to use a drone to replace your cellphone with a piece of uranium that’s shaped like a cellphone

That reads differently after 2024.

[–] [email protected] 44 points 1 week ago (1 children)

many reasons, for example

multidimensional arrays
arrays of function pointers
pass by reference of a pointer

[–] xmunk 6 points 1 week ago* (last edited 1 week ago) (1 children)

In two of your cases this operator is pretty shit because at some point you'll probably want to offset the access (this isn't a knock at you but at the feature).

This operator would only really be relevant to the last case which rarely comes up outside of infrastructure/library work (building a tool building tool) and usually those code bases are cautious to adopt new features too quickly anyways for portability.

I've done serious C++ work (not much in the past decade though) - while references are absolutely amazing and you essentially want to pass by const ref by default I think well written maintainable C++ should maybe have a dozen heap objects tops. C++ is a better language if you generally forget that pointers and bare arrays exist.

Just again - I think you're right and the fact that your list is only three things long (and arguably two of them would be misuses) is a pretty clear sign that this is an incredibly niche feature.

[–] [email protected] 16 points 1 week ago* (last edited 1 week ago) (1 children)

I don't think this operator is a real feature, tbh 😅

[–] [email protected] 6 points 1 week ago

The fact that he claims it's in C++ 29, while we are in 2024 is a good hint.

Or maybe he is a time traveler. Quick, go ask the next lottery numbers!

[–] [email protected] 17 points 1 week ago* (last edited 1 week ago) (1 children)

Because stuff can own other stuff and be owned at the same time. Also, arcane jackarsery.

Edit: if you want to give a function a pointer that it may change this may occur in a constructive way. I.e. replace an owned object.

[–] [email protected] 5 points 1 week ago (1 children)

Yeah... But it's usually a good practice to put a struct somewhere between your 30 levels of ownership.

Exceptions exist, but they are not very common. Also, in C++, operators overloading may help you if you keep needing to write code like this.

[–] [email protected] 3 points 6 days ago (1 children)

In C++ you should never have owning raw pointers. Unless you have a good reason™.

Raw pointers are great, but not for ownership.

[–] [email protected] 6 points 6 days ago* (last edited 6 days ago) (1 children)

I just use unique_ptr 99% of the time

[–] [email protected] 4 points 6 days ago

And you should.

It even works for classes whose constructors your implementation cannot see, if you aren't a bitch about it.

[–] fibojoly 12 points 1 week ago

Pointer to pointer is fairly common stuff once you get serious with C++ but I've no idea what this abomination is supposed to even be, haha!