TR: The idea behind C++ was that programmers would work harder in return for more-efficient code. Bell Labs wanted a language that a few really smart people would use to write code that would run on computers like Electronic Switching Systems (ESS) that weren’t very fast. Today, there are a lot of software developers and computers are very fast. Does that vitiate the point of C++?
BS: C++ wasn’t designed specifically for the large switching machines, but for a huge range of applications. Bell Labs was the home of an incredible range of interesting projects spanning every scale and using essentially every kind of computer and operating system. But yes, the average Bell Labs programmer was significantly more able than most people’s notion of an “average programmer,” and reliability and performance (in that order) were considered significantly more important than in most other places.
Performance is still an issue in many of the applications that I’m interested in: responsiveness of interfaces, start-up and close-down time of applications. Software developers have neutralized the astounding performance of modern computer hardware by adding layer upon layer of overelaborate [software] abstractions. We seem to have hit the limits of linear speedup for hardware, but in many cases, we could win a couple of orders of magnitude back from the software.
That said, C++ has indeed become too “expert friendly” at a time where the degree of effective formal education of the average software developer has declined. However, the solution is not to dumb down the programming languages but to use a variety of programming languages and educate more experts. There has to be languages for those experts to use–and C++ is one of those languages.
TR: In retrospect, in designing C++, wasn’t your decision to trade off programmer efficiency, security, and software reliability for run time performance a fundamental mistake?
BS: Well, I don’t think I made such a trade-off. I want elegant and efficient code. Sometimes I get it. These dichotomies (between efficiency versus correctness, efficiency versus programmer time, efficiency versus high-level, et cetera.) are bogus.
What I did do was to design C++ as first of all a systems programming language: I wanted to be able to write device drivers, embedded systems, and other code that needed to use hardware directly. Next, I wanted C++ to be a good language for designing tools. That required flexibility and performance, but also the ability to express elegant interfaces. My view was that to do higher-level stuff, to build complete applications, you first needed to buy, build, or borrow libraries providing appropriate abstractions. Often, when people have trouble with C++, the real problem is that they don’t have appropriate libraries–or that they can’t find the libraries that are available.
Other languages have tried to more directly support high-level applications.
That works, but often that support comes at the cost of specialization. Personally, I wouldn’t design a tool that could do only what I wanted–I aim for generality.