RE: [boost] Formal Review: Template Metaprogramming Library (MPL)

From: Aleksey Gurtovoy (agurtovoy_at_[hidden])
Date: 2002-07-18 17:08:31

Giovanni Bajo wrote:
> I'm specifically puzzled about why sometimes "_" is used, and 
> other times "_1", "_2", etc are used. For example:
> 
> if_<less<_1, _2>, _1, _2>  // min<>
> 
> but:
> 
> replace_if<seq, less<_, int_c<4> >, int_c<4> >   // low_clamp<4>
> 

Oh, this one is easy - both unnamed and numbered placeholder notations are
supported (although it's not recommended to mix the two in the same
expression :). I'll post a deeper description of the semantics of both forms
tonight.

> Also, I'm badly missing a reference for copy<> and copy_if<> :)

Oh, I wondered if anybody cares about those or not ;). Will add.

> Also, is deref<T>::type the same as T::type? 

Yes.

Aleksey