RE: [boost] Re: Empty sequence elements

From: Paul Mensonides (pmenso57_at_[hidden])
Date: 2005-03-03 03:47:20

> -----Original Message-----
> From: boost-bounces_at_[hidden] 
> [mailto:boost-bounces_at_[hidden]] On Behalf Of Tobias Schwinger

> Thank you for this very detailed reply !
> 
> Is it safe to use BOOST_PP_EMTPY or 
> BOOST_PP_INDENTITY(somthing) as the element and "dereference" 
> with '()' ?

Sure, provided that the result is never "bound" to an argument by itself.  E.g.

#define A(x) B(x)
#define B(x) x

A() // undefined: empty argument to A

A( BOOST_PP_EMPTY() ) // undefined: empty argument to B

A( BOOST_PP_EMPTY )() // okay

Regards,
Paul Mensonides