Re: [boost] Preprocessor: documentation comment

From: David Abrahams (david.abrahams_at_[hidden])
Date: 2002-06-13 17:50:07

From: "Paul Mensonides" <pmenso57_at_[hidden]>

> > 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

Cool! But does this announcement have any relationship to the post you
quoted?

-Dave