On Thu, Jun 19, 2008 at 11:41:52PM +0200, Dag Lindbo wrote:
Hello again!
Here comes another suggestion about the DOLFIN public interface:
Constructing time dependent functions by subclassing from Function and
TimeDependent is very very nice. The way u.sync(t) works by storing a
pointer to t is also very clever. However, I think it is too clever --
most would expect pass-by-value semantics when passing a scalar to a
function. A very simple change could make it a lot clearer what's going
on: Pass a pointer to t instead of a constant reference. This forces the
user to take the address of the scalar, which really shows what's going
on. E.g.
u.sync(&t)
Today I misunderstood the reference nature of sync(t), and wrote code like
this:
while(t < T){
"compute timestep"
t += dt
sync_bc(t)
}
void sync_bc(real t){
for "all Dirichlet BCs"
bc.sync(t) // Pointer to stack memory gets assigned!!!!
}
:-( Of course, no one would be foolish enough to pass a pointer to stack
memory knowingly in such a short lived context.
/Dag
TimeDependent does not seem to be used anywhere in the code so now
it's just a fancy way of storing the current time. Objects that want
to store the current time could equally well just add a member
real t;
I suggest we remove TimeDependent for now and add it back later when
we find any use for it.
ok?
