[J3] another PURE example

Malcolm Cohen malcolm at nag-j.co.jp
Tue Oct 6 03:00:03 EDT 2020


>I am thinking derived types are local identifiers and thus 'TINIT' is a different type than 'T'. 


1.	Derived types are not identifiers.
2.	Whether you have a rename or not, there is a local identifier for a local entity that is use-associated with the module entity.
3.	The rules for whether two types are “the same type” are spelled out in clause 7, in particular, in Determination of derived types. This is non-trivial for SEQUENCE types.
4.	At first glance, Robert’s two type definitions appear to satisfy the requirements for the two type definitions to be the same.




..............Malcolm Cohen, NAG Oxford/Tokyo.


From: J3 <j3-bounces at mailman.j3-fortran.org> On Behalf Of Vipul Parekh via J3
Sent: Tuesday, October 6, 2020 2:38 PM
To: General J3 interest list <j3 at mailman.j3-fortran.org>
Cc: Vipul Parekh <parekhvs at gmail.com>
Subject: Re: [J3] another PURE example



On Mon, Oct 5, 2020 at 6:13 PM Robert Corbett via J3 <j3 at mailman.j3-fortran.org <mailto:j3 at mailman.j3-fortran.org> > wrote:

      USE T1
      USE T2, TINIT => T
        TYPE(T) Y
        Y = TINIT()
        Y%P = 2.0



Hi Bob.


At first glance, your assignment instruction 'Y = TINIT()' looks non-conforming to me.


I am thinking derived types are local identifiers and thus 'TINIT' is a different type than 'T'.  Since there is no defined assignment, the TKR rules for intrinsic assignment aren't being followed with the 'Y = TINIT()' assignment.  Now, if you implement a defined assignment, you won't be able to make it a PURE procedure and yet shallow/deep copy the POINTER component.  And without a PURE defined assignment, you won't be able to do what you are doing in your 'SUBR' procedure.  Thus the semantics of PURE looks Ok as captured in the standard?


Some food for thought?

Vipul Parekh  



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