C++ Reference Guide

A Response to Linus Torvalds' C++ Diatribe

Last updated Nov 14, 2008.

In what has become a cult show, Linus Torvalds attacks C++ every now and then, repeating more or less the same claims. In his latest diatribe he said: "C++ is a horrible language. It's made more horrible by the fact that a lot of substandard programmers use it, to the point where it's much much easier to generate total and utter crap with it. Quite frankly, even if the choice of C were to do nothing but keep the C++ programmers out, that in itself would be a huge reason to use C."

Here's Steven Dewhurst's reply to Linus Torvalds' criticism:

I think it's only fair to point out that Linus' diatribe is more than a year old, and he has spoken in more measured and printable tones elsewhere about the same subject. Less excusable, however, is that he makes the claim that C++ cannot be used in resource-constrained areas with nothing but anecdotal evidence to support his claim. Linus has done good work and has earned his soap box, but he also has a professional obligation to make sense while he’s holding forth. (For those who follow such things, this is an instance of Gotcha #12, “Adolescent Behavior,” from C++ Gotchas.)

The argument that abstraction and efficiency are mutually-exclusive or that they're mutually exclusive in the context of C++ is demonstrably false. Lately, much of my work involves writing embedded code in C++ with heavy use of inheritance and templates, and the results have been more than promising. The resultant code is typically smaller and faster than the equivalent (well-written) C code provided by the board's manufacturer, and has the significant advantage of being usable by a developer who is not expert in the minutia of the board's design. Unlike Linus, I haven't written a commercial OS, but I have written a policy-based, pre-emptive tasker in C++. It occupies just 3k of RAM and is pretty zippy in addition to being easy to understand, customize, and maintain. Just to annoy people like Linus, I've also used typelist meta-algorithms to generate exception handlers with identical efficiency to hand-coded C. In a number of recent talks given at the Embedded Systems conferences, I've shown that commonly-criticized C++ language features can significantly outperform the C analogs. As an old-school, Bell Labs C hacker I've nothing against C. But C++ provides tools and capabilities that are hard to come by in C, and often make it easier for a competent C++ programmer to produce cleaner and typically smaller and faster code than the C equivalent.

Regarding competence, Linus’s implied argument that C++ attracts bad programmers the way other things attract flies is, in spite of the effective metaphor, both unfair and a little over the top. Inexperienced or incompetent programmers have been lured into writing bad code in other languages as well; I've inherited my share of poorly designed and rendered C. There's no question that C++ is a significantly larger and more complex language than C, and a competent C++ programmer should be familiar with many more design styles (including, among others, that "idiotic 'object model' crap") than a competent C programmer. Wider experience with different design approaches and coding idioms is an advantage if the programmer actually has more than a passing understanding of the techniques. Problems typically arise when teams of competent C programmers are thrown onto a C++ project without adequate preparation simply because C++ syntax looks something like C syntax. The results are usually about the same as you’d get by throwing the same team into a COBOL project. But you’re not going to catch me criticizing COBOL. That’s Linus’s job.