(j3.2006) statement labels and scope

[Bill Long]

On Jan 14, 2016, at 3:46 PM, Van Snyder <Van.Snyder at jpl.nasa.gov> wrote:

> If I remember the discussion about "scope" and "inclusive scope," labels
> of format statements concerned us more than branch targets.
> 

A common style is to group format statements at the end of a program unit, which could be far away from the block.  Allowing reuse of the same label for a format statement inside the block seems like a programmer-friendly feature.  This seems to argue that the text in 3.2.5 is intentionally ?scope? and not ?inclusive scope?.   Thanks for the history/background, Van.

Cheers,
Bill



> On Thu, 2016-01-14 at 21:40 +0000, Bill Long wrote:
>> On Jan 14, 2016, at 3:09 PM, Lionel, Steve <steve.lionel at intel.com> wrote:
>> 
>>> Um, what about:
>>> 
>>> subroutine sub
>>> 
>>> block
>>> go to 10
>>> 10 continue
>>> end block
>>> 
>>> 10 continue
>>> end subroutine sub
>> 
>> 
>> I?d argue that the text for labels would say the branch is to the
>> continue statement inside the block.  As if the statements inside the
>> BLOCK construct were, instead, in a contained internal procedure. 
>> 
>>> 
>>> The text for GO TO says "inclusive scope?.
>> 
>> 
>> Point taken.  Making the rules for labels and GOTO (the primary user
>> of labels)  consistent would be less confusing.  (Although any code
>> using GOTO statements is already headed down the ?confusing? path.)
>> 
>> The advantage of the current wording for labels is that you can insert
>> statement labels inside a block without having to look at the code in
>> the surrounding scope to search for label conflicts.  Only if you want
>> to branch to a statement outside the block construct would you have to
>> be careful to not use that label on a statement inside the block as
>> well. 
>> 
>> The main question is whether the text in 3.2.5p2 needs a change, and
>> if it does, is an incompatibility notice also needed?
>> 
>> Cheers,
>> Bill
>> 
>> 
>>> 
>>> Steve
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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
>> 
>> 
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> 
> 
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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