[boost] [preprocessor] What syntax to present to the user

From: Loïc Joly (loic.actarus.joly_at_[hidden])
Date: 2005-05-13 05:22:07

Hello everybody,

I'm trying to use the boost preprocessor library to allow the user to 
define "rich" enums, for instance enums that cannot be converted to int, 
whose values can be displayed in human readable form on a stream...

I think I have to use macro to ease the writing of such enums, and I 
decided it was a good occasion to learn boost::preprocessor. My first 
impression : Wow ! You guys really use magic when programming !

Now, I have to decide what will be the interfaces for such rich enums. 
My (unreachable) goal would be something like that :
RichEnum Type{Val1, Val2, Val3};

A little bit more reasonnable (but still unacheivable, I believe) goal 
would be :
RICH_ENUM(Type, Val1, Val2, Val3);

I think I can come up with several possible writing :

1/
RICH_ENUM(Type, (Val1)(Val2)(Val3));
2/
RICH_ENUM(Type, 3, (Val1,Val2,Val3));

3/
#define NAME Type
#define VALUES (Val1)(Val2)(Val3)
#include "RichEnum.h"
#undef NAME
#undef VALUES

4/ same as 3/, but with tuple syntax for VALUES

With 1/ and 2/, all the class declaration is on the same line, which 
could decrease debugability. With 3/ and 4/, I can write it one several 
lines.

And now, the questions :
Which writing do you think would be best ? Why ? Are there other 
possibilities I overlooked ? Is is possible to have a syntax like 1/ and 
2/ with good debugability ?

Regards,

-- 
Loïc