[ET Trac] [Einstein Toolkit] #675: allow zero timelevels in STORAGE when timelevels are specified via parameter

[Einstein Toolkit]

#675: allow zero timelevels in STORAGE when timelevels are specified via
parameter
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 Reporter:  rhaas        |       Owner:     
     Type:  enhancement  |      Status:  new
 Priority:  minor        |   Milestone:     
Component:  Cactus       |     Version:     
 Keywords:               |  
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 this allows to simply set timelevels=0 to turn off storage without having
 to put an "if(do_something || timelevels > 0)" into schedule.ccl files. It
 is also the only way to turn off storage inside of a GROUP of SCHEDULE
 statement based on a condition (other than scheduling the item twice, once
 with STORAGE, once without).

 More complicated conditions require either (I believe):
 a. the (ab)use of accumulors the way that GRHydro::GRHydro_hydro_excision
 works (only all "and" or all "or" supported I think)
 a. using undocumented behaviour and putting C code into schedule.ccl
 {{{
 const int compound_condition = condition_a || condition_b ? 3 : 2
 SCHEDULE
 {
   STORAGE foo[compound_condition]
 ...
 }}}
 c. allow more than just identifiers within the '[]" brackets of STORAGE
 (most likely one has to allow almost everything "{{{[^]]+}}}") then use
 C's "?" operator to build up the complicated expression

 Having 0 timelevels works trivially since eventually these STORAGE
 statements end up in CCTK_GroupStorageIncrease which allows 0 timelevels.

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/675>
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