(j3.2006) derived types with type parameters are different
Tue Jul 29 07:04:49 EDT 2008
In the original parameterised types proposals SEQUENCE was not allowed, thereby avoiding these
problems. Unfortunately in my opinion it was later included.
> -----Original Message-----
> From: j3-bounces at j3-fortran.org [mailto:j3-bounces at j3-fortran.org]On
> Behalf Of Bill Long
> Sent: 28 July 2008 18:03
> To: Robert.Corbett at sun.com; fortran standards email list for J3
> Subject: Re: (j3.2006) derived types with type parameters are different
> Robert Corbett wrote:
> > After spending more time than I should have searching for a good
> > solution to this problem, I have concluded that there are no good
> > solutions. I have decided that the best fix for the problem is
> > to ban sequence types with type parameters from standard-conforming
> > programs. Given the permissive nature of the Fortran standard,
> > vendors who currently implement sequence types with type parameters
> > could continue to support them unchanged.
> I'm not sure what is being proposed here. Is it
> 1) An Interp for Fortran 2003 along the lines of "you guys really didn't
> intend to allow this; it is certainly a mistake in the standard..." or
> 2) A comment for Fortran 2008 that we should make an incompatible change
> that removes this capability.
> > Most of the solutions I considered would require large changes to
> > the standard,
> I would not consider something that requires large changes to the
> standard to be a "solution".
> > would impose a large burden on implementors,
> "did impose" for those who already did this, "would impose" for the rest.
> > and
> > would be hard for users to understand.
> As compared to, for example, finalizers ?
> > Simple solutions, such as
> > considering all derived type definitions with type parameters to
> > define different types, would almost certainly break all
> > existing implementations of parameterized sequence types. Given
> > that parameterized sequence types add negligible functionality to
> > the language, why bother?
> I think the time for that argument was about 6 years ago.
> > Bob Corbett
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> Bill Long longb at cray.com
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