[simias]

I'm a former C++ dev who went all in on Rust. I think the main problem is that the learning curve works in Rust's disadvantage here.

If you start learning C++ it's relatively smooth sailing at first, especially if you're already familiar with C. Basic OOP, basic RAII, inheritance, virtual functions, basic templates. Easy peasy.

It's once you start getting to the advanced topics that the footguns become apparent. The sometimes intricate resolution rules (and how they compound with template substitution rules), the various subtleties surrounding copy constructors, const, mutable, concurrency and the way they play with each others, the various quirks inherited from C that sometimes don't play very well with modern constructs etc...

Rust is the other way around. There's a very steep curve right at the start where you need to understand how the borrow checker works and how to make it happy. You have to learn the right mindset right away. You need to get over that to reach the "fearless confidence" goodness.

I think that's going to be a big problem for experienced C++ coders to do the jump (especially if you need to convince multiple devs to make the jump at the same time).

It kind of reminds me of the switch from SVN to git. At first I didn't get it, git felt a lot more complicated and I didn't really see the benefit compared to good old SVN. Of course after a few years I'd curse under my breath every time I had to use SVN for some legacy codebase, it feels so clunky and limited now that I'm familiar with a proper git workflow.

[adrianN]

Already basic C contains more than enough footguns. If you think basic C++ is relatively free of footguns you're kidding yourself. Rust has a steep learning curve because the compiler nags you a lot about things that would have been a potential footgun in C. Unfortunately it is not smart enough to see in all cases that your code wouldn't have triggered that particular footgun and has to be overly conservative.

[simias]

I meant that basic C++ seems rather straightforward and at first doesn't appear to introduce too many new footguns over the C subset. Actually thanks to vectors and RAII it can remove whole classes of classic C mistakes.

It's only when you start to have all these elements work (or not work) together that you realize that it's not as simple as it first seemed and the various side effects, overloadings and implied constraints sprinkled throughout the code turned it into a virtual minefield.

Case in point, this video I've watched the past week: https://channel9.msdn.com/posts/C-and-Beyond-2012-Herb-Sutte...

It's a very interesting talk (and probably worth a watch if you're a C++ developer) but the amusing thing to me is that he begins by showing two short pieces of rather simple C++ code and asks the audience if they are UB or not. Seems like nobody can (or want to) answer that question.

Spoiler: the conclusion of the talk is that one of these pieces of code is only legal if the copy constructor of the custom type adheres to certain implied constraints that are not enforced by the compiler and, it seems, few people are aware of.

[lucozade]

Not to belabour the metaphor or anything but if your footartillery doesn't fire, you still have feet.

This is probably the point that simias is making and I tend to agree. It's straightforward to get a simple C++ program working with decent performance if you know C. And RAII, std::vec etc makes you feel quite productive.

Now, at some point you'll notice that debug and release don't act the same way. Occasionally. Or you try to add threading to a single-threaded program. Then the love will die (due to bloodloss from blowing off the whole leg). But that's often after months of reasonably productive development.

Rust, to a large extent, will prevent you from ever getting to that state and that's a very good thing. But the upfront cost is quite high. My guess is that those of us who have experienced the C++ pain will appreciate the value that that cost is buying.

But I'm hopeful that Rust will draw a wider audience primarily because of your last point. It's really quite conservative at present. The NLS work is already expanding the scope of acceptable programs and, I presume, that what is learnt from that effort will seed further work in that space.

[pdpi]

C++ gives you an embarrassment of footgun riches above and beyond what C provides. On the other hand, idiomatic modern C++ also deftly avoids many of the C pitfalls. e.g. You don't ever touch new, delete, or raw pointers — instead favouring RAII-based smart pointers, and references. You avoid arrays in favour of vectors. This style (as opposed to old-school C-with-classes C++) is way more productive, and way safer.

[nickik]

As somebody who tried his hands on C++ a couple of times only I have to say that basic RAII, templates and virtual functions are not really easy. I mean maybe compared to even worse stuff in C++, but compared to almost every other language, they are still a pain.

[simias]

Well I was mostly talking from a C dev standpoint. At first I think it's easy to think of C++ as "C with classes". It just feels like syntactical sugar for stuff you'd do in C. RAII just means calling a destructor function at the end of the scope. Virtual functions are like stuffing function pointers in structs, templates are like "macros on steroid" etc... It's like C with some stuff on top.

Of course it turns out that it's a lot more complicated and powerful than that and it's probably the wrong way to look at C++ but it might take a while until you realize that you're not in Kansas anymore. Rust on the other hand forces you to become acquainted with its paradigm right away, unless you're willing to put all your code in unsafe blocks.

[conn01]

I hope there is a new language which combine "C++" + "thread safe and mem safe". That will be a killer language

[unrealhoang]

There is. The name is Rust, I heard