[J3] [EXTERNAL] Re: Self-assignment of allocatable component

[Damian Rouson]

And that demonstrates the problem with metrics!  Good point, Malcolm.

Damian

On Thu, Jul 29, 2021 at 6:10 PM Malcolm Cohen via J3 <
j3 at mailman.j3-fortran.org> wrote:

> Actually, by that measure, the single most expensive statement is the END
> statement.
>
>
>
> Every single example program has at least one of those, and often many
> more!
>
>
>
> Cheers,
>
> --
>
> ..............Malcolm Cohen, NAG Oxford/Tokyo.
>
>
>
> *From:* J3 <j3-bounces at mailman.j3-fortran.org> *On Behalf Of *Clune,
> Thomas L. (GSFC-6101) via J3
> *Sent:* Thursday, July 29, 2021 9:27 PM
> *To:* General J3 interest list <j3 at mailman.j3-fortran.org>
> *Cc:* Clune, Thomas L. (GSFC-6101) <thomas.l.clune at nasa.gov>
> *Subject:* Re: [J3] [EXTERNAL] Re: Self-assignment of allocatable
> component
>
>
>
> Ah,  but by the same measure, are Fortran’s pointers “less expensive” than
> C pointers?     Maybe allowing for a normalization factor based on the
> relative size of the 2 communities.
>
>
>
> *From: *J3 <j3-bounces at mailman.j3-fortran.org> on behalf of j3 <
> j3 at mailman.j3-fortran.org>
> *Reply-To: *j3 <j3 at mailman.j3-fortran.org>
> *Date: *Wednesday, July 28, 2021 at 11:44 PM
> *To: *j3 <j3 at mailman.j3-fortran.org>
> *Cc: *Damian Rouson <damian at sourceryinstitute.org>
> *Subject: *[EXTERNAL] Re: [J3] Self-assignment of allocatable component
>
>
>
> As one measure of the cost and complexity associated with a feature,
> someday I would love to see a count or a percentage of the of the emails on
> this list in response to a question roughly equal to “Is this code
> standard-conforming?” for code that involves a pointer.  By the suggested
> measure, I nominate pointers for the single most expensive feature in the
> history of Fortran.
>
>
>
> Damian
>
>
>
> Sent from my iPhone
>
>
>
>
> On Jul 28, 2021, at 06:55, Vipul Parekh via J3 <j3 at mailman.j3-fortran.org>
> wrote:
>
>
>
> On Wed, Jul 28, 2021 at 9:01 AM Daniel C Chen via J3 <
> j3 at mailman.j3-fortran.org> wrote:
>
> Thanks Malcolm and all for the clarification.
> ..
>
> From: "Malcolm Cohen via J3" <j3 at mailman.j3-fortran.org>
> To: "'General J3 interest list'" <j3 at mailman.j3-fortran.org>..
>
> Hi Daniel,
>
> Yes, you are quite right, so in that case, X=X would involve at least
>
> 1.       Capturing the value of X%I,
>
> 2.       Finalising X%I,
>
> 3.       Restoring the value of X%I. ..
>
>
>
>  Hi Daniel and Malcolm,
>
>
>
> Interesting discussion.  If I understood the clarification thus far
> correctly, the following program seems to me to conform - would you agree?
>
>
>
>  module m
>
>    type :: t
>       character(len=10) :: objname = ""
>       integer :: dat = 0
>    contains
>       final :: finalize_t
>    end type
>    type, extends(t) :: u
>    end type
> contains
>    impure elemental subroutine finalize_t( this )
>       type(t), intent(inout) :: this
>       print *, "t::finalize_t invoked for ", this%objname
>    end subroutine
> end module
> module n
>    use m
>    type :: v
>       class(t), allocatable :: i
>    end type
> contains
>    subroutine sub()
>       type(v) :: x, y
>       allocate( t :: x%i ) ; x%i%objname = "x%i" ; x%i%dat = 42
>       allocate( u :: y%i ) ; y%i%objname = "y%i"
>       if ( allocated(y%i) ) then
>          print *, "Initially, y%i%dat = ", y%i%dat, "; expected is 0"
>       end if
>       y = x ; y%i%objname = "y%i"
>       if ( allocated(y%i) ) then
>          print *, "y%i%dat = ", y%i%dat, "; expected is 42"
>       end if
>    end subroutine
> end module
>    use n
>    call sub()
> end
>
>
>
> And the program output per the standard might be as follows - note the
> order of the last 2 lines in the output can be ignored:
>
>  Initially, y%i%dat =            0 ; expected is 0
>  t::finalize_t invoked for y%i
>  y%i%dat =           42 ; expected is 42
>  t::finalize_t invoked for y%i
>  t::finalize_t invoked for x%i
>
>
>
> However only one out of several processors I tried gave the above output.
> There is variance among the rest when it comes to output from the (impure)
> finalizer.  Is the expected output I list above conformant, or is that the
> other processors are yet to conform to the standard when it comes to
> finalization?
>
>
>
> Daniel, is it possible for you to check the IBM processor with this
> example and provide your feedback and comments?
>
>
>
> Thanks,
>
> Vipul
>
>
>
> *Disclaimer*
>
> The Numerical Algorithms Group Ltd is a company registered in England and
> Wales with company number 1249803. The registered office is: 30 St. Giles,
> Oxford, OX1 3LE, United Kingdom. Please see our Privacy Notice
> <https://www.nag.co.uk/content/privacy-notice> for information on how we
> process personal data and for details of how to stop or limit
> communications from us.
>
> This e-mail has been scanned for all viruses and malware, and may have
> been automatically archived by Mimecast Ltd, an innovator in Software as a
> Service (SaaS) for business.
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.j3-fortran.org/pipermail/j3/attachments/20210729/d3554350/attachment.htm>