On Tuesday April 26 2011 08:16:29 Garth N. Wells wrote:
> On 26/04/11 16:07, Anders Logg wrote:
> > On Tue, Apr 26, 2011 at 03:59:52PM +0100, Garth N. Wells wrote:
> >> On 26/04/11 15:55, Anders Logg wrote:
> >>> On Tue, Apr 26, 2011 at 03:45:22PM +0100, Garth N. Wells wrote:
> >>>> On 26/04/11 13:51, Anders Logg wrote:
> >>>>> On Tue, Apr 26, 2011 at 02:00:50PM +0200, Anders Logg wrote:
> >>>>>> It feels good that you trust me enough to handle it. ;-)
> >>>>>>
> >>>>>> Will add it sometime this afternoon and then we can revisit the JIT
> >>>>>> compiler caching.
> >>>>>
> >>>>> I'm getting confused here... Looking at preprocess.py in UFL, I see
this:
> >>>> It is confusing. Does the function 'preprocess' do anything that the
> >>>> old FormData class didn't? It would be easier to follow if Form just
> >>>> had a member function form_data() that computes and stores data (like
> >>>> it used to), or if Form had a 'preprocess' function. Having the
> >>>> function preprocess return a new form is really confusing.
> >>>
> >>> I don't find that particularly confusing. It's the same as
> >>>
> >>> refined_mesh = refine(mesh)
> >>
> >> Which is the whole problem. By creating a new object, FormData is thrown
> >> away. The preprocessing should just compute some more data, just like we
> >> *don't* do
> >>
> >> initialised_mesh = mesh.init(0)
> >>
> >> What was wrong with Martin's original design that necessitated the
> >> change?
> >
> > As I explained, I thought it was better to have an explicit call to
> > preprocess since that makes it clear that one makes a call to a
> > function which may take some time to execute (instead of just calling
> > a member function which seems to just return some data).
> >
> > But as I say above: I added the caching back at some point (maybe even
> > the day after I removed it 2 years ago) so we don't need to discuss
> > why I removed it (as I realized myself I shouldn't have removed it and
> > added it back a long time ago).
> >
> > What has me confused now is that the caching seems to be in place but
> > we still need the extra caching in FFC/DOLFIN and I don't see why.
>
> Because preprocess returns a new form, e.g. define a form
>
> a = u*v*dx
> jit(a)
>
> Inside jit,
>
> a.form_data() is None:
> b = preprocess(a) # b now has data attached, but a doesn't
> else:
> b = a
>
> Now 'b' has been preprocessed, and has form data attached, but 'a'
> doesn't. Calling 'jit(a)' again, the code will never enter the 'else'
> part of the clause because 'a' never gets any form data. Johan has added
> some code FFC that attaches the form data of 'b' to 'a', but it is a bit
> clumsy.
No, it was already attached. I just made ffc use it.
> Better would be
>
> a.preprocess()
>
> or
>
> a.form_data()
As already mentioned in a previous email, I suggest we only call form_data().
This will return the form_data. The preprocessed form is attached to the
form_data and this is what is passed to the code generator. I am pretty sure
this is what was there from the beginning.
It is confusing to call:
form = preprocess(form)
as the preprocessed form was never ment to be doing anything but being passed
to the code generator, AFAIK.
Johan
> Garth
>
> > --
> > Anders
> >
> >> Garth
> >>
> >>>> Garth
> >>>>
> >>>>> def preprocess(form, object_names={}, common_cell=None):
> >>>>> ...
> >>>>>
> >>>>> # Check that form is not already preprocessed
> >>>>>
> >>>>> if form.form_data() is not None:
> >>>>> debug("Form is already preprocessed. Not updating form
> >>>>> data.") return form
> >>>>>
> >>>>> ...
> >>>>>
> >>>>> # Attach form data to form
> >>>>> form._form_data = form_data
> >>>>>
> >>>>> # Attach preprocessed form to form data
> >>>>> form_data._form = form
> >>>>>
> >>>>> And when I look at the blamelist (bzr annotate), it looks like I
> >>>>> added those lines, so I must have come to my senses and added it
> >>>>> back at some point (way back). So in conclusion, calling
> >>>>> preprocess() should not taking any time.
> >>>>>
> >>>>> What am I missing?
>
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