Re: OT: Language War (Re: "C" Manual)
Lo, on Wednesday, January 2, Ben Collins did write:
> Just because in C it can cause a segfault doesn't mean the other
> languages are any better.
No, it doesn't. However, IMNSHO, the fact that C and C++ have many
*more* undefined constructs that other languages does mean that the
other languages are better (in most situations).
> Show me one language that doesn't have some action that is classified
> as undefined.
I'm not aware of any, although PLT Scheme (http://www.plt-scheme.org/)
comes pretty close. So what? I never claimed that other languages are
completely defined; I simply said that the construct I mentioned
up-thread has undefined behavior in C and C++, and that this lack of
definition is dangerous. (The few places where PLT Scheme's behavior is
undefined are also dangerous, but they arise much less
frequently---when's the last time you tried to invoke a continuation
from within one of dynamic-wind's guard thunks?)
> Documenting that something is undefined is called a specification.
Yes, in one sense, you're right. But it's a pretty useless
specification. `We specify that we do not specify what this construct
does.' I don't see how this is supposed to be helpful. If I had a
compiler that flagged all undefined constructs at compile-time so that I
didn't make them through careless errors, that would be one thing.
Unfortunately, that's not possible, because you can't *detect* all of
C's undefined constructs at compile-time.
> It is there so you know that you cannot rely on certain behavior. If
> you ignore that, then no language is going to help you.
Look, I'm not trying to ignore the fact that the ANSI/ISO C spec marks
certain constructs as undefined. I'm saying that the fact that they are
undefined is not acceptable, especially when other languages
specifically define the behavior of the analogous constructs. The fact
that the behavior of these constructions is completely specified by the
language means that I catch errors much earlier, whereas with C, I may
not catch them at all.
The main issue: I'm tired of getting bogus output with no indication
that it's bogus, and I'm tired of spending long hours tracking down
silly pointer bugs that aren't an issue in more sophisticated languages.
The more undefined constructs in my language, the more time I have to
spend doing this kind of grunt work. It's not that I want the computer
to do my entire job for me, but I would like it to do some of the grunt
work so I can concentrate on the interesting, challenging, and above all
*useful* parts of the program.
Richard
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