RFC: small syscons and kbd patch

[Eygene Ryabinkin]

Garret,

Fri, Dec 05, 2008 at 12:50:38AM -0800, Garrett Cooper wrote:
> 1. What dialect of C was it defined in? Is it still used in the
> standard dialect (honestly, this is the first time I've ever seen it
> before, but then again I am a younger generation user)?

It is the standard negation operator: !(expr) is equal to (expr == 0).

> 2. Is it still taught in schools (I didn't learn it when I was taught
> C)?

Yes.  I am personally teaching the people in school and I am explaining
the concept of double negation every two years ;))

> If not in schools, what about the Richie text (it's sort of like
> the defacto C programming standard book of course)?

K&R book is good but it at no means covers all tricks and idioms
of a C language.

> 3. What's the real loss of going to `? :', beyond maybe 3 extra
> keystrokes if it's easier for folks who may not be as experienced to
> read?

No real loss, just easier to type and looks more compact.  It is the
matter of a personal taste, I think.

If one knows this idiom, he will recognize it at a glance.  If not, one
should think a bit about the logics behind it, but it shouldn't be hard:
almost everyone uses constructs like 'if (!ptr)'.  And there is only one
step from there to the double negation.
-- 
Eygene
 _                ___       _.--.   #
 \`.|\..----...-'`   `-._.-'_.-'`   #  Remember that it is hard
 /  ' `         ,       __.--'      #  to read the on-line manual   
 )/' _/     \   `-_,   /            #  while single-stepping the kernel.
 `-'" `"\_  ,_.-;_.-\_ ',  fsc/as   #
     _.-'_./   {_.'   ; /           #    -- FreeBSD Developers handbook 
    {_.-``-'         {_/            #
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