[ET Trac] [Einstein Toolkit] #1333: Fortran module in GRHydro_InterfacesM.h is nonsensical

[Einstein Toolkit]

#1333: Fortran module in GRHydro_InterfacesM.h is nonsensical
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  Reporter:  rhaas                  |       Owner:            
      Type:  defect                 |      Status:  new       
  Priority:  critical               |   Milestone:  ET_2013_05
 Component:  EinsteinToolkit thorn  |     Version:            
Resolution:                         |    Keywords:  GRHydro   
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Changes (by eschnett):

  * priority:  major => critical
  * milestone:  => ET_2013_05


Comment:

 It is not legal in Fortran to define the same module twice. The situation
 is the same as defining two routines with the same name -- this is a
 fundamental "don't". I am raising the severity of this. I also consider
 this a blocker for the release.

 I understand that people strive to structure Fortran code in a manner
 similar to C code, but unfortunately that doesn't work. Instead of
 defining stand-alone subroutines, and then declaring interfaces (and
 repeating much code), it is far superior to define subroutines INSIDE a
 module, and then using that module when the subroutine is to be called.
 Include files should not be necessary at all for this.

 The drawback of this is that Cactus cannot call subroutines that are
 defined in a module, it only knows how to call stand-alone subroutines
 (however, this can be changed). That is, all scheduled or externally
 visible routines need to be stand-alone routines.

-- 
Ticket URL: <https://trac.einsteintoolkit.org/ticket/1333#comment:1>
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