Re: [boost] Preprocessor: documentation comment

From: Paul Mensonides (pmenso57_at_[hidden])
Date: 2002-06-13 17:16:46

> Vesa,
>
> Thanks for implementing Paul's automatic recursion technique! However, doc
> remarks like:
>
>     2D and 3D repetition
>     BOOST_PP_REPEAT() implements automatic recursion. 2D and 3D repetition
> are directly supported.
>
> are just confusing if you don't already know about the problems being
> solved under-the-covers. There's no clue what "recursion" means in this
> context, for example.
>
> -Dave

I implemented an equality check as a constant time operation using the same type
of technique and emailed a sample to Vesa (the current version uses WHILE).  It
basically hinges on this fact:  EQUAL(x, y) ... if MACRO_y will not expand
inside MACRO_x, then x must be equal to y.  Using this constant-time operation
equality check, I reimplemented TUPLE_ELEM, making the implementation
significantly easier to expand to higher values.  The current implementation
uses the brute force approach:

GET_ELEM_0_FROM_TUPLE_OF_SIZE_1
GET_ELEM_0_FROM_TUPLE_OF_SIZE_2

// etc. etc.

Paul Mensonides