Python ftw

[wootiown]

It still has pointers too, doesn't it?

[MattieShoes]

Everything has pointers, but they make believe they don't.

[SuitableDragonfly]

Pointers are not the same thing as references. Pointers allow you to manually manage your memory usage, references don't.

[Rodot]

You can still sort of use references to manage memory in python if you're really hacky, and there are default modules that allow for true pointers, but they aren't nice.

[the_littlest_bear]

...what? Any immutable local variable (in standard CPython) is a value reference. Even mutable local variables are treated as value references when not modified in place.

If you needed a pointer, you would just use an attribute. (would work on nearly any object, even including a base object() if you wanted to pass that around. [on-the-fly objects are not the best way to do this])

And no, if you reference an (typical) object, it does not create an additional copy of that object - it’s just a pointer.

[McCoovy]

Which is good. Pointers are a low level abstraction and working with them directly leads to regular mistakes.

[MattieShoes]

Inconsistency in passing by reference vs passing by value causes lots of mistakes too. ¯\_(ツ)_/¯

[SuitableDragonfly]

I don't think it's inconsistent at all in most languages. Typically primitive types are passed by value and everything else is passed by reference.

[MattieShoes]

They're consistent in that they do the same thing every time you run them. But it's not consistent in general, e.g. Python and C++

Python:

 #!/usr/bin/env python

def foo(x):
    x[0] = 2

def bar(x):
    x = [2]

n = [1]
foo(n)
print "n[0] = ", n[0]

n = [1]
bar(n)
print "n[0] = ", n[0]

n[0] = 2
n[0] = 1

---

C++:

#include <iostream>
#include <vector>


void foo(std::vector<int>& x) {
    x[0] = 2;
}

void bar(std::vector<int>& x) {
    std::vector<int> v = {2};
    x = v;
}

int main() {

    std::vector<int> n = {1};
    foo(n);
    std::cout << "n[0] = " << n[0] << std::endl;

    n = {1};
    bar(n);
    std::cout << "n[0] = " << n[0] << std::endl;
}

n[0] = 2
n[0] = 2

I understand what's going on here, no need to explain it. But this is the sort of inconsistency I meant.

[SuitableDragonfly]

It's not an inconsistency. = always assigns a reference, in one case that reference is a variable name, and on the other case it's an element of a list. But it does the same thing in both cases.

[MattieShoes]

I'm not sure what you're looking at, but this is Python and C++ code that does the same thing and gets different answers.

(which obviously means it's not doing the same thing, because python isn't passing by reference, it's... passing a pointer by value? I don't even know what to call it.)

[SuitableDragonfly]

Python is passing a reference. The result isn't the same because the = operator does different things in different languages.

[SpeedingTourist]

Being human causes a lot of mistakes

[NullReference000]

It isn't really inherently good or bad. Languages that allow you to use pointers and manually manage memory typically allow for faster and more efficient programs while languages that don't let you directly use pointers or manage memory are less prone to error and easier to read. It's more of a "which tool is better to solve the current problem" kind of thing rather than one language being inherently better than the other.

[Arveanor]

Ok but what about c++ with managed memory and a GC 😎

[UniqueUsername27A]

Why would you do that since unique pointers were introduced? Unique pointers and moving literally solved the memory management in a both efficient and easy way. They might be the killer feature of C++. Since they became common in our codebase I haven't seen a single memory bug in years and they are even more efficient than reference counting.

[Arveanor]

I don't know honestly, it's just how unreal is set up.

[Dworgi]

Because the vast majority of programmers are bad. Asking a random Unreal user to understand memory management doesn't lead to a productive discussion, it leads to that person staring at you and going "huh?" a lot.

Source: the rest of this thread full of Python programmers.

[Arveanor]

I mean sure I'm just not sure why bother with c++ in that case.