[TylerGlaiel]

All that the C++ committee needed to do was just introduce "import" as "this is the same as include except no context can leak into it".

Would have been dirt simple to migrate existing codebases over to using it (find and replace include with import, mostly), and initial implementations of it on the compiler side could have been nearly identical to what's already there, while offering some easy space for optimizing it significantly.

Instead they wanted to make an entirely new thing that's impossible to retrofit into existing projects so its basically DOA

[reactordev]

That could be said of every additional c++ feature since c++0x.

The committee has taken backwards compatibility, backwards - refusing to introduce any nuance change in favor of a completely new modus operandi. Which never jives with existing ways of doing things because no one wants to fix that 20 year old codebase.

[feelamee]

if no one wants to fix this 20yo codebase, why is there someone who wants to push it to the new C++ standard?

[Maken]

The goal is to be able to import that 20yo battle-tested library into your C++20 codebase and it just works.

[anon-3988]

Hyrum law would dictate that your C++20 now becomes C++11 or whatever is the oldest in the whole chain of dependency.

[Maken]

That's kind of the point of C++'s retro-compatibility: C++20 contains new additions to the C++11 standard. Unless you rely in mistakes in the standard like auto_ptr or faulty atomics, which should be fixed regardless of the C++ standard, your C++11 dependencies are perfectly valid C++20 and do not block the new shiny toys.

[feelamee]

there are really a lot of simpler solutions than switching the standard of the whole codebase. E.g. write wrapper which interface doesn't require a new standard.

[reactordev]

Mmm pimpl’s and acne…

[reactordev]

You have it backwards. Everyone wants a new standard but no one wants to fix the code to make it work with a new way. They would rather introduce a whole new thing.

We want new stuff, but in order to do that we must break old stuff. Like breaking old habits, except this one will never die.

[bluGill]

we spent a billion dollars to rewrite our code breaking everything. 15 years latter and we have a better product than the old stuff- but 15 years ago was pre c++11, and rust didn't exist. i cannot honestly ask for another billion dollars to repeat that again and we are stuck. We must keep the old code running and if your new thing isn't compatible with whatever we did back then you are off the table.

c++26 still builds and runs that c++98 and so we can use it. Rust is nice but it can't interoperate as well in many ways and so it gets little use. you can call that bad desingn - I might even agree - but we are stuck.

[reactordev]

This. This is why C++ is stuck. The effort required to rewrite old shit code (that works, does its job, makes money) is just too valuable to the company so it sits. All vendors must conform or else be shown the door. No innovation can take place so long as Clu has its claws in our company.

I empathize. This is where rust could really help but there’s a lot of hate around “new” so it sits. The C++2042 standard will still have to be able to solve for C++98. The language will die. A pointer is a pointer and it shouldn’t need weak_ptr, shared_ptr, unique_ptr etc. If you expose it, it’s shared. If you don’t, then it could be unique but let the compiler decide. The issue with all these additions is they are opt in for a community that would rather opt out since it means learning/rewriting/refactoring.

I’ve come across this so many times in my career. Thank goodness for AI and LLMs that can quickly decompose these hairball code bases (just don’t ask it to add to it).

I love C/C++ but it’s so old at this point that no sane person should ever start with that.

[StilesCrisis]

If you think the problem with C++ is that shared_ptr exists, you should probably just use C.

[StilesCrisis]

My experience has been that everyone _wants_ to fix the 20 year old codebase! But it’s hard to justify putting engineers on nebulous refactoring projects that don’t directly add value.

[reactordev]

This I understand. The risk of revenue loss if not done right, the risk of revenue loss if not done at all.

[account42]

No it can't be said for most other C++14+ features as they are actually implemented and used in real code bases.

[reactordev]

Touché, but why the 4 different pointer containers?

[imtringued]

What do you mean by "no context can leak into it"? Do you mean it shouldn't export transitive imports?

As in `#include <vector>` also performs `#include <iterator>` but `import vector` would only import vector, requiring you to `import iterator`, if you wanted to assign `vec.begin()` to a variable?

Or is it more like it shouldn't matter in which order you do an import and that preprocessor directives in an importing file shouldn't affect the imported file?

[ninkendo]

Not GP, but I take it to mean I can’t do:

    #define private public
    #import <iostream> // muahaha

Or any such nonsense. Nothing I define with the preprocessor before importing something should effect how that something is interpreted, which means not just #define’s, but import ordering too. (Importing a before b should be the same as importing b before a.) Probably tons of other minutiae, but “not leaking context into the import” is a pretty succinct way of putting it.

[TylerGlaiel]

yeah that, include is a textual replacement, so anything placed before the include is seen by all the code in the include. Not just other preprocessor stuff and pragmas but all of the other function definitions as well. There are some cases where this has legitimate use, but also is one of the main reasons why compilers can't just "compile the .h files separately and reuse that work whenever its included, automatically"

you define #import as "include but no context leaks into it" and that should on its own be enough to let the compiler just, compile that file once and reuse it wherever else its imported. That's like 95% of the benefit of what modules offered but much much simpler