[boost] Re: mpl::vector & push_back question ?

From: Aleksey Gurtovoy (agurtovoy_at_[hidden])
Date: 2005-03-01 06:07:11

Zhang, Karl writes:
> Hi:
>
> When I am reading mpl source code. I notice that push_bck algorithm,
> Look as following:
>
> template<>
> struct push_back_traits< aux::vector_tag >
> {
>     template< typename Vector, typename T > struct algorithm
>     {
>         typedef vector_node<T,Vector> type;
>     };
> };
>
> My question is: when generate new sequence, vactor_node<T, vector>,
> why skip "size" argument ?  How does it increase sequence size in
> push_back?
>
> About push_front, It increase sequence size when generating new
> sequence.

Karl,

Are you looking at pre-1.32 version of the library? Things have
changed quite a bit since then, and I'm afraid I don't remember the
details of the older versions of the code that well by now. It might
have been that the 'size' argument was only present in one of the two
alternative vector implementations and the said difference between
'push_front' and 'push_back' was in fact a difference between two
different implementation strategies, which would be quite easy to miss
unless you are deeply familiar with the code.

Generally, it's much easier for me to answer questions about library
implementation if they refer to the code in the latest release.

-- 
Aleksey Gurtovoy
MetaCommunications Engineering