[ET Trac] [Einstein Toolkit] #223: Make declaration of CCTK_ARGUMENTS safer

[Einstein Toolkit]

#223: Make declaration of CCTK_ARGUMENTS safer
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  Reporter:  eschnett     |       Owner:        
      Type:  enhancement  |      Status:  review
  Priority:  minor        |   Milestone:        
 Component:  Cactus       |     Version:        
Resolution:               |    Keywords:        
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Comment (by hinder):

 This change is a very good idea and should be implemented.

 Process:

 For the benefit of anyone reading cGH-const.diff, I think the first,
 second and fourth hunks can be ignored, as they don't seem to be related
 to this change.  I'm not sure what the first hunk is doing, but it is not
 just a formatting change, so should probably not be committed without
 being remarked on or put into a separate patch.

 Content:

 I'm a bit confused about the relation between the summary and comments and
 the patches.  The summary says that cctkGH is made const, whereas it looks
 to me like the patch makes the local variables which are computed from
 cctkGH const.  My naive interpretation would be that you could still
 modify variables if you accessed them via cctkGH->... and this seems to be
 what the CartGrid3D patch is doing.  When you say in comment:2 that
 CartGrid3D and Time need to be modified, are you talking about a further
 modification to CartGrid3D beyond the current patch, for example one that
 casts away constness?

 The approach taken in the patch looks to me like a good one, and should
 help to avoid nasty user bugs.  Is there a similar patch for the Time
 thorn, as the summary indicates that this will be needed before these can
 be committed.  Also, for such a pervasive change, running the ET test
 suite on a couple of architectures might shake out any problems before
 users running on trunk get bitten by them.  Do you want to just commit
 this and see what falls out, or test it thoroughly before it is committed?

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/223#comment:7>
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