Re: OT: Open letter to the Linux World

From: Alexander Holler
Date: Thu Sep 04 2014 - 14:11:45 EST

Am 04.09.2014 19:58, schrieb Austin S Hemmelgarn:
On 2014-09-04 13:29, Alexander Holler wrote:
Am 04.09.2014 16:36, schrieb Austin S Hemmelgarn:
On 2014-09-04 06:16, Alexander Holler wrote:

It's a myth that C++ ends up in bigger code than C. At least in my
experience. Especially when the latest additions to C++ are in effect
(like the move-semantics in C++11 I like quiet a lot and which you get
almost for free (by changing nothing) when you use the STL). Thread
support is now also standardized (in C++11), quiet nice to use.

Assuming you are writing in a standalone environment (no standard
libraries), then yes, your code will usually be about the same size
(unless you go way overboard with the object-oriented stuff); but the
runtime is larger in almost all non-standalone environments, and there
are some cases that code does end up larger in C++. A lot of 'Clean C'
(stuff written so that it compiles correctly as C, C++ and Objective C)
that I have seen seems to end up larger (by about 4-6%) when built as
C++ (although it usually does much worse as Objective C).

There are always corner cases and I never would use some "Clean C" code
to compare sizes of C and C++. There is a whole lot of stuff you just
can't, shouldn't or wouldn't do when using C instead of C++.

And just throwing in some numbers without any explanation about features
(like exceptions), optimizations and so on you've enabled for the tests
you used to get those numbers, doesn't work. ;)

I can't really comment on what you mean with "standalone environment" or
"non-standalone environment", as I don't know what you mean with that.
But if several programms share e.g. the stuff which is in libstdc++.
you'll get a lot of size back when compared with C-only programms where
everyone invents the wheel again and again.
By standalone environment, I mean no libraries, no libc[++], no external
dependencies, and in the case of a lot of kernel programming, no
built-ins. A OS kernel HAS to be written like that, and it's easier to
do that in C than C++. I doubt that you have ever looked at any source
code for Windows drivers, but Windows is written in C++, and they still
are just as mind-numbingly insane as some of the poorly maintained,
vendor originated Linux drivers.

I've seen drivers for Windows and for OS2/2 and DOS and FreeBSD and ...

But throwing the ball back, did you know that all Arduino SW is in C++? ;)

Not all C is like the Linux kernel, and in fact, if you use Linux,
probably more than half of your user-space programs were written in C.
They use dynamic linking just like C++ programs (but often with less
complex symbol mangling).

This thread isn't about the kernel, but some userspace program which does quiet a lot and which wants to do even more. I've just used one example I did in the kernel space to explain what I miss when I'm using or having to use C instead of C++.

I do understand why the Linux kernel is (still) in C and don't want to start a discussion about that.


Alexander Holler
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