On 21 Dec 2011, at 18:33, Johan Hake <[email protected]> wrote:
> On Wednesday December 21 2011 18:00:23 Garth N. Wells wrote: >> What happens behind the scenes when for >> >> x = Vector(100) >> >> ones does >> >> x[:] >> >> ? > > That depends if x[:] is on the lhs or on the rhs. If it is on the rhs a copy > will be returned. This is a slice convention in Python. > > l0 = range(5) > l1 = l[:] > l1[0] = 1 > > The last statement will change l1 but not l0. I would expect the same for > dolfin vectors. > > If it is on lhs and the rhs is either a GeneriVector or a scalar, > x._assign(rhs) will be envoked. What if I do x[:] += 1.0 ? Garth > > The relevant methods in la_post.i are: > > def __getslice__(...): > def __setslize__(...): > > Johan > > >> I've added GenericVector operator+= and -= for doubles, and would like >> to be sure that this can be used from Python without unnecessary >> copies being made. >> >> Garth >> >> _______________________________________________ >> Mailing list: https://launchpad.net/~dolfin >> Post to : [email protected] >> Unsubscribe : https://launchpad.net/~dolfin >> More help : https://help.launchpad.net/ListHelp _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : [email protected] Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
