(j3.2006) (SC22WG5.5029) WG5 vote on draft TS on further coarray features

Van Snyder van.snyder
Sun Jul 21 18:33:11 EDT 2013

An alternative to a new this_team() intrinsic, or executing a FORM 
SUBTEAM statement, is a team variable in ISO_Fortran_env, whose value is 
the initial team.

I still think the idea of putting "team_variable ::" ahead of 
cosubscripts is a bad idea.  I would rather see a syntax for 
coassociation, along the lines of the ASSOCIATE statement, in the CHANGE 
TEAM statement.

This discussion worries me.  Like King Ronald, we've mounted our horse 
and are thundering down the road in every direction, designing stuff 
that nobody understands yet.  It looks like much of this stuff has had 
only a few moments' reflection before being proposed to be cast in 
concrete.  Sure, Cray might have done some of it already, and their 
customers might use it successfully, but that doesn't mean it's the best 
solution, or even a good one.

I'd rather see more discussion, introspection, consensus, and 
experience,  and less controversy, before we rush to publish a 
definitive solution as a Technical Specification that is almost promised 
to end up as part of the standard.

Tobias Burnus wrote:
> Bill Long wrote:
>> If the application needs a name for the initial team, you can form a
>> team in the main program with every image specifying the same team (1).
>>     For the purposes of cosubscripts, this team is the same as the
>> initial team.
> I somehow thought that one additionally needs a "change team", but I now 
> think that a "form subteam" should be sufficient - which makes the code 
> cleaner than I initially feared.
> Thus, the advantage of the proposed new intrinsic (e.g. "this_team()") 
> is smaller.
> PRO new intrinsic: The code is clearer than "form subteam(1, var)". And 
> it avoids a synchronization (which is relatively slow)
> CON new intrinsic: It pollutes the namespace without providing a 
> substantial new features.
> Tobias
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