JiscMail Logo
Email discussion lists for the UK Education and Research communities

Help for COMP-FORTRAN-90 Archives


COMP-FORTRAN-90 Archives

COMP-FORTRAN-90 Archives


COMP-FORTRAN-90@JISCMAIL.AC.UK


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Proportional Font

LISTSERV Archives

LISTSERV Archives

COMP-FORTRAN-90 Home

COMP-FORTRAN-90 Home

COMP-FORTRAN-90  2000

COMP-FORTRAN-90 2000

Options

Subscribe or Unsubscribe

Subscribe or Unsubscribe

Log In

Log In

Get Password

Get Password

Subject:

Re: internal procedures as actual arguments

From:

"Kurt W. Hirchert" <[log in to unmask]>

Reply-To:

Kurt W. Hirchert

Date:

Wed, 19 Jan 2000 10:01:00 -0500

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (63 lines)

At 10:23 PM 1/18/00 +0100, Phillip Helbig wrote:
>My response would be, allow it for non-recursive hosts.  I guess the 
>motivation for disallowing (obsolete) statement functions is similar; 
>why are generic names not allowed?  Does this restriction also apply to 
>intrinsic generics?

The motivation for statement functions was different -- statement functions
are typically implemented by in-line expansion, so there is manifestation
with standard calling sequence to associate with the dummy procedure.

Generics are a collection of specific procedures with rules to decide which
specific procedure should be called for particular arguments.  The
committee felt it would be awkward, at best, to support generic dummy
procedures that would associate with the totality of that information.

There is one case where a generic name can be used as an actual argument
associated with a (specific) dummy procedure - if the name is both generic
and specific (e.g., "sin" is both the name of the generic sine function and
the name of the specific function that calculates the sine function for
default real arguments), it can be used as an actual argument denoting the
specific procedure.

These rules and restrictions apply to intrinsic generics in the same way as
user-written generics.  (Note, however, that some intrinsic procedures are
restricted from being used as actual arguments even if the specific name is
available.)

If the procedure being called and the dummy procedure are both explicit,
one could argue that one should be able to pass a generic and have the
"right" part of the generic be associated with the dummy procedure, but
this gets complicated in the general case.  (For example, the dummy
procedure might accept a single argument while the "corresponding" specific
in the generic might have two dummy arguments with the second one
optional.)  Rather than make the compiler deal with all the strange cases,
the committee chose to require the programmer to explicitly create a
specific procedure that invokes the generic procedure.  This decision could
be revisited, but there hasn't been much (any?) demand for this so far.
>
...
>> There was, however, a remark inserted in Annex C that if a processor
>> implements the ability to pass internal procedures as actual arguments,
>> then deep binding should be used to determine the correct instance of
>> the host environment.
>
>OK, but this would be non-portable and non-standard.

1. This was the f90 committee's way of telling future committees that if
they remove the restriction in a future revision, the resulting behavior
should be consistent with deep binding.

2. This was the f90 committee's way of telling implementors that if the
restriction is removed in the future, it will require deep binding, so any
extensions implemented in this area now should also use deep binding to
avoid being incompatible with future standards.

You're quite right that this does not give you anything portable to use now.
--
Kurt W. Hirchert                          [log in to unmask]
Center for Computational Sciences                +606-257-8748


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Top of Message | Previous Page | Permalink

JiscMail Tools


RSS Feeds and Sharing


Advanced Options


Archives

December 2023
February 2023
November 2022
September 2022
February 2022
January 2022
June 2021
November 2020
September 2020
June 2020
May 2020
April 2020
December 2019
October 2019
September 2019
March 2019
February 2019
January 2019
November 2018
October 2018
September 2018
August 2018
July 2018
May 2018
April 2018
March 2018
February 2018
January 2018
December 2017
November 2017
October 2017
September 2017
August 2017
July 2017
June 2017
May 2017
April 2017
March 2017
January 2017
December 2016
November 2016
October 2016
September 2016
August 2016
July 2016
June 2016
May 2016
April 2016
March 2016
February 2016
December 2015
November 2015
October 2015
September 2015
August 2015
June 2015
April 2015
March 2015
January 2015
December 2014
November 2014
October 2014
August 2014
July 2014
May 2014
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
July 2013
June 2013
May 2013
April 2013
February 2013
January 2013
December 2012
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
April 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
August 2010
July 2010
June 2010
March 2010
February 2010
January 2010
December 2009
October 2009
August 2009
July 2009
June 2009
March 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
August 2008
July 2008
June 2008
May 2008
April 2008
March 2008
February 2008
December 2007
November 2007
October 2007
September 2007
August 2007
July 2007
June 2007
May 2007
April 2007
March 2007
January 2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997


JiscMail is a Jisc service.

View our service policies at https://www.jiscmail.ac.uk/policyandsecurity/ and Jisc's privacy policy at https://www.jisc.ac.uk/website/privacy-notice

For help and support help@jisc.ac.uk

Secured by F-Secure Anti-Virus CataList Email List Search Powered by the LISTSERV Email List Manager