Re: Why use C++?

[Hyman Rosen <hyrosen@mail.com>]

On 8/12/2011 4:32 AM, Georg Bauhaus wrote:
> #define RGB_LIMIT 3
>
> typedef unsigned char Intensity;
> enum RGB {Red, Green, Blue};
> typedef Intensity Pixel[RGB_LIMIT];

I might do this instead as

     typedef unsigned char Intensity;
     enum RGB_Index { Red, Green, Blue, N_RGB_Index };
     typedef Intensity Pixel[N_RGB_Index];

which avoids the need for a macro and ties the number of
intensities in the array directly to its enumerated index.

> switch (1) { case 0: break; case CHAR_BIT == 8: break; }

Oh, that's cute! It's going right into my bag of tricks :-)
You don't need the breaks, though:

     switch (1) { case 0: case CHAR_BIT == 8: ; }

And with C++, you don't need executable code:

// Probe template
template <bool tf> struct probe { };
template <> struct probe<true> { typedef int t; };

// test for 8-bit char
typedef probe<CHAR_BIT == 8>::t is_char_8_bit;

> If I am a beginner, what is the number of technicalities I
 > must know it order to understand the second way of declaring
 > things?

A few; of course, when I was a complete Ada beginner (not that
I'm much more than that now) I was always thrown by the use of
apostrophes as attribute designators. When I see

     for Intensity'Size use 8;

it makes me want to go off searching for where the string ends
and trying to figure out what's going on. I also don't know that
a beginner finds the notion of an enumerated type declared as an
array index to be immediately obvious.

> (I'll leave out that the declare-like-used rule in typedef is
> confusing many. Maybe that's because the typdef-ed name isn't in some
> fixed position in the typedef.)