[ublas] What's the advantage of using array_adaptor?

From: Hongzheng Wang (wanghz_at_[hidden])
Date: 2008-06-01 03:17:29

Hi,

I scanned the archives of mailing lists for the usage of
array_adaptor<>.  It seems that the typical usage is as the following
codes:

double extdat[N];
array_adaptor<double> aa(N, extdat);
vector<double, array_adaptor<double> > vd(N, aa);

By tracing the codes, I found that aa and extdat are sharing the same
raw data.  That is, &aa.data()[0] points to extdat.  But vd does not
shares the data.  Instead, when vd is constructed, it seems that a
copy of extdat is created to setup the new vector.  So, I wonder what
is the advantage of using array_adaptor.  In other words, why not just
use std::copy or even memcopy (if the layouts are contiguous) to do
the same thing?  Is there any special design purpose in inventing
array_adaptor?

Thanks in advance.

-- 
HZ