I admit I was impressed with your dataflow-fu! To me, the memory map
approach seemed much simpler. Of course, I haven't implemented either. :-)
On Mon, Oct 24, 2016 at 4:17 PM, Diab Jerius <[email protected]>
wrote:
> Chris,
>
> I've looked into your second suggestion, and what I've discovered is
> that while I understand what you mean, I haven't the foggiest idea of
> how to implement it.
>
> Diab
>
>
> On Tue, Oct 11, 2016 at 10:30 AM, Diab Jerius <[email protected]>
> wrote:
> > Chris,
> >
> > Your second suggestion seems like an interesting approach as it uses
> > existing machinery. I'll take a look at that.
> >
> > On Fri, Oct 7, 2016 at 10:40 PM, Chris Marshall <[email protected]>
> wrote:
> >> A few thoughts:
> >>
> >> - Use flexmap with the right options to memory
> >> map the piddle data so any write would be interrupted
> >> by the permissions on the file
> >>
> >> - Maybe you could use a virtual, affine piddle
> >> with the data flow back to the parent disabled
> >> and with a barf or some such (Craig would have
> >> a better idea on how this could/might work...
> >>
> >> - This seems like something good to add to the
> >> PDL Next Gen required features...
> >>
> >> --Chris
> >>
> >>
> >> On 10/7/2016 18:19, Zakariyya Mughal wrote:
> >>>
> >>> On 2016-10-07 at 17:35:04 -0400, Diab Jerius wrote:
> >>>>
> >>>> [my apologies, forgot to send to list]
> >>>>
> >>>>
> >>>> ---------- Forwarded message ----------
> >>>> From: Diab Jerius <[email protected]>
> >>>> Date: Fri, Oct 7, 2016 at 3:52 PM
> >>>> Subject: Re: [Pdl-general] Read only piddles?
> >>>> To: Craig DeForest <[email protected]>
> >>>>
> >>>>
> >>>> On Fri, Oct 7, 2016 at 1:00 PM, Craig DeForest
> >>>> <[email protected]> wrote:
> >>>>>
> >>>>> I don’t think that there is at the moment.
> >>>>>
> >>>>> It might be possible to mark a PDL read-only to prevent modification
> of
> >>>>> its contents, but modification as you describe involves a Perl-level
> change
> >>>>> to the variable: putting a new value in the variable is not
> something that
> >>>>> PDL controls.
> >>>
> >>> Perhaps you could look at using the mprotect() syscall on the PDL's
> data?
> >>> You will likely have to allocate it yourself in C so that it is
> >>> page-aligned. There is an example of how to do this at
> >>> <http://eli.thegreenplace.net/2013/11/05/how-to-jit-an-introduction>.
> >>>
> >>>> That's what I feared. I would like to prevent an inadvertent
> >>>>
> >>>> $pdl *= 3;
> >>>>
> >>>> I started out with a PDL subclass and overriding as many core methods
> >>>> and operator overloads that I could think of, but that's a chase with
> >>>> no end.
> >>>
> >>> This way would be really tricky to do. It would possibly have to take
> >>> into consideration the `inplace` flag and the signature of each
> function
> >>> under the PDL namespace.
> >>>
> >>> I've found that PDL subclassing is very tricky to do in a way that
> >>> restricts by certain properties. To do it right, we need a more
> >>> principled approach to defining the functions as pure and impure
> >>> functions and some sort of (contract? role-based?) mechanism to
> indicate
> >>> the kinds of data that a particular operation can be applied on (like
> >>> statistical levels of measurements).
> >>>
> >>> I'm still thinking about how to approach this --- it seems tricky to do
> >>> while still remaining fast. Especially when simultaneously thinking
> >>> about refactoring PDL!
> >>>
> >>> Scala and Haskell have done very interesting things in this area that
> we
> >>> need to steal. ;-)
> >>>
> >>> Regards,
> >>> - Zaki Mughal
> >>>
> >>>>> You could make a Perl copy of the PDL and hand *that* off:
> >>>>>
> >>>>> $tmp = $my_pdl;
> >>>>> untrusted($tmp);
> >>>>>
> >>>> Unfortunately, the piddles may be large and the calls may be many.
> >>>> I'm trying to avoid too much memory thrashing.
> >>>>
> >>>>
> >>>>>> On Oct 7, 2016, at 10:27 AM, Diab Jerius <[email protected]>
> >>>>>> wrote:
> >>>>>>
> >>>>>> I've got an application where I need to maintain a functional
> >>>>>> relationship between several piddles, but need to hand them over to
> >>>>>> untrusted code which will destroy that relationship if the piddles
> are
> >>>>>> modified.
> >>>>>>
> >>>>>> Is there any means of marking a piddle as read only?
> >>>>>>
> >>>>>> Thanks,
> >>>>>>
> >>>>>> Diab
> >>>>>>
> >>>>>>
> >>>>>> ------------------------------------------------------------
> ------------------
> >>>>>> Check out the vibrant tech community on one of the world's most
> >>>>>> engaging tech sites, SlashDot.org! http://sdm.link/slashdot
> >>>>>> _______________________________________________
> >>>>>> pdl-general mailing list
> >>>>>> [email protected]
> >>>>>> https://lists.sourceforge.net/lists/listinfo/pdl-general
> >>>>>>
> >>>>
> >>>> ------------------------------------------------------------
> ------------------
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> >>>> [email protected]
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> >>>
> >>>
> >>> ------------------------------------------------------------
> ------------------
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> >>
> >>
>
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