[En-Nut-Discussion] Do we realy need "include/net/errno.h"

[duane ellis]

Ole Reinhardt>  do we realy need include/net/errno.h?
Harrald> avr-libc 1.6.4 and earlier as well as ICCAVR provide just

[basically - different compilers have different things... agh.... cross 
compile builds are painful]

I've had to deal with this before, one *COULD* use ./configure 
[shudder]. However, there is a simple trick that solves this *nicely* it 
is as follows, and *many* non-unix hacks can easily understand and 
follow it:

============================
Create a new "header" directory, call it NUT.

Applications have a choice:

option1:    #include <stdio.h>

In the OPTION 1 case - it is not portable.
    It works, and everybody is happy - life goes on.

**OR**

option2:    #include <nut/stdio.h>

Option #2, solves portability issues.

For example:       #include <nut/stdint.h>

Here's the advantage, OPTION #2 - is now "safe" - and cross platform, in 
effect, <nut/stdint.h> becomes a wrapper that fixes all problems with 
*THAT* compilers version of *THAT* header file.

you also don't have to play games with INCLUDE search path order... and 
stuff like that.

The example <Nut/stdint.h> might read as follows:

===============
#ifndef  NUT_STDINT_H
#define NUT_STDINT_H

#if defined(__GNU_GCC_MAJOR > 4 )
    // all versions of GCC after 4.0 have stdint.h
   #include <stdint.h>
#define NUT_STDINT_DONE 1
#endif

// the defines here are contrived to show the example - they are not 
valid names
#if defined( __MS_VISUAL_STUDIO )
   // visual studio is brain dead, it does not have stdint.
  // use our fixers
   #if  __X86_32_BIT
          #include <nut/stdint32_bit_helpers.h>
    #endif
    #if __X86_64BIT
          #inlcude <nut/stdint64_bit_helpers.h>
    #endif
#define NUT_STDINT_DONE 1
#endif

#if !defined(NUT_STDINT_DONE)
#error "Sorry STDINT is not setup for this compiler yet"
#endif

#endif  // NUTSTDINT_H
===============

In a *PERFECT*WORLD* - it might read like this instead:

   #ifndef NUT_STDIO_H
   #define NUT_STDIO_H
   // we live in a perfect world
   #include <stdio.h>
   #endif

===============

The trick here is this, if you need a "standard header file" - ie: 
ERRNO, or STDINT, or whatever... you include it, via the "NUT" *wrapper* 
version - which - *WILL* include the proper one eventually.

BUT - it may also contain all the required #ifdefs and other wackyness 
to make it very portable.

-Duane.