(j3.2006) Clarify F08/0147 ?

[Bill Long]

On Nov 12, 2015, at 2:17 AM, Cohen Malcolm <malcolm at nag-j.co.jp> wrote:

> Hi Bill,
> 
> Your understanding (1) and (2) is the same as mine.  For (3), I would word 
> it as
>  "For a defined assignment statement, auto-reallocation of allocatables 
> does not occur, as that is only done by an intrinsic assignment statement.?

This occurred to me as well after sending the initial email. I agree this is clearer and more direct.


> 
> How about adding the following extra paragraph to the answer?
> 
>  "With these edits, both of the statements A and B are defined assignment 
> statements.  Auto-reallocation of allocatable variables only occurs as part 
> of an intrinsic assignment statement, so while statement A is conforming 
> (because the shapes are the same), statement B is not conforming (because 
> the shapes differ).?

Yes, I think this would be helpful.  An extra sentence of explanation can be valuable to someone who goes back to look at the interp much later, and has forgotten the discussion.

Cheers,
Bill


> 
> Cheers,
> 
> -----Original Message----- 
> From: Bill Long
> Sent: Wednesday, November 4, 2015 7:08 AM
> To: fortran standards email list for J3
> Subject: (j3.2006) Clarify F08/0147 ?
> 
> In working through the test case in Interp F08/0147, I think I understand 
> the change, but the words I was looking for are not part of the answer.  The 
> test case is:
> 
> Module da_module
>    Type t
>      Real c
>    End Type
>    Interface Assignment(=)
>      Module Procedure edasgn
>    End Interface
>  Contains
>    Elemental Subroutine edasgn(a,b)
>      Class(t),Intent(Out) :: a
>      Class(t),Intent(In) :: b
>      a%c = -b%c
>    End Subroutine
>  End Module
>  Program edatest
>    Call test(10,10,13)
>  Contains
>    Subroutine test(n,n2,m)
>      Use da_module
>      Type(t) :: x(n),z(m)
>      Type(t),Allocatable :: y(:)
>      x%c = [ (i,i=1,n) ]
>      z%c = [ (i,i=1,m) ]
>      Allocate(y(n2),Source=t(0))
>      y = x                        ! A
>      Print 1,y
>    1 Format(*(1X,F0.1,:))
>      y = z                        ! B
>      Print 1,y
>    End Subroutine
>  End Program
> 
> With the change made by the edits, it appears that
> 
> 1) The assignment A is defined assignment and is conforming (from first 
> edit).
> 
> 2) The assignment B is not standard conforming, since the shapes are not the 
> same (from second edit).
> 
> 3) Effectively, auto-reallcation on assignment will not occur if the 
> assignment is defined assignment and the subroutine is elemental (since the 
> shapes already agree).
> 
> All of which is fine with me.
> 
> Cheers,
> Bill
> 
> 
> Bill Long 
> longb at cray.com
> Fortran Technical Support  &                                  voice: 
> 651-605-9024
> Bioinformatics Software Development                     fax:  651-605-9142
> Cray Inc./ Cray Plaza, Suite 210/ 380 Jackson St./ St. Paul, MN 55101
> 
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> -- 
> ........................Malcolm Cohen, Nihon NAG, Tokyo. 
> 
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Bill Long                                                                       longb at cray.com
Fortran Technical Support  &                                  voice:  651-605-9024
Bioinformatics Software Development                     fax:  651-605-9142
Cray Inc./ Cray Plaza, Suite 210/ 380 Jackson St./ St. Paul, MN 55101