[ET Trac] [Einstein Toolkit] #1651: Problems with expansions in parameter files

[Einstein Toolkit]

#1651: Problems with expansions in parameter files
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 Reporter:  hinder  |       Owner:                     
     Type:  defect  |      Status:  new                
 Priority:  major   |   Milestone:                     
Component:  Cactus  |     Version:  development version
 Keywords:          |  
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 If I have a parameter file containing
 {{{
 CoordBase::ymin = -CoordBase::dy * 2
 CoordBase::dy = 0.1
 }}}
 it looks like Cactus silently ignores the CoordBase::dy in
 CoordBase::ymin, and tries to set ymin = 2, presumably because dy has not
 been set "yet".  This raises two points:

 1. The parser should raise a fatal error if it does not have a value for a
 parameter it is expanding;
 2. The order of parameters listed in the parameter file should not matter.

 I think that parameter files should be declarative rather than imperative;
 i.e. you should think of them as a static mapping from parameter names to
 values rather than as a program which sets (and resets?) variables in the
 sequence written in the parameter file.  A simple way to transform the
 current "set each parameter in sequence" implementation would be to sort
 the assignments so that parameters are set before they are used, and to
 raise a fatal error if a parameter is set twice.  Would it be possible to
 implement this?

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/1651>
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