> So, which specific problems requires you to both optimize the hell out of your CPU and memory, and mostly work at a higher level of abstraction than C?
My sibling here already mentioned AAA game development. Finance is another area where top performance is often required.
Performance is the requirement. Being able to work at an abstraction level higher than C is highly desirable. C++ gives you both of those.
> I'll go even further: C + <high-level language of choice> already competes on that front (abstraction + performance). On which specific problems are they not enough, and C++ is required?
You get a boundary between the "high level" and "performance oriented" parts of the code that is arbitrary and only exists because the high level language performs poorly. There are definite costs to that approach.
> I'll go even further: there has been a number of C pre-processors spouting up recently.
Cute hacks that are probably not suitable for production use.
Let's be honest here. You're asking for problems that require the use of C++ now. The situation is surely going to be different in, say, five years from now - though I don't think it'll be a "C with classes".
My sibling here already mentioned AAA game development. Finance is another area where top performance is often required.
Performance is the requirement. Being able to work at an abstraction level higher than C is highly desirable. C++ gives you both of those.
> I'll go even further: C + <high-level language of choice> already competes on that front (abstraction + performance). On which specific problems are they not enough, and C++ is required?
You get a boundary between the "high level" and "performance oriented" parts of the code that is arbitrary and only exists because the high level language performs poorly. There are definite costs to that approach.
> I'll go even further: there has been a number of C pre-processors spouting up recently.
Cute hacks that are probably not suitable for production use.
Let's be honest here. You're asking for problems that require the use of C++ now. The situation is surely going to be different in, say, five years from now - though I don't think it'll be a "C with classes".