[petsc-users] Printing _some_ options

[Barry Smith]

  Hm, what is the advantage of dropping bags? Maybe we just need to improve bags to make them better for you.

> On Jul 22, 2025, at 10:23 AM, Blaise Bourdin <bourdin at mcmaster.ca> wrote:
> 
> Hi,
> 
> My (Fortran) code currently makes heavy use of PetscBag to store parameters and options in fortran derived types. I would like to simplify it by getting rid of these bags and simply querying the PETSc options database as needed.
> 
> One nice thing about PetscBags, though, is that I can easily display help messages related to a specific family of options by calling PetscBagView and get nicely formatted output like this:
> 
> Registering cell set    1 prefix: cs0001_ 
> PetscBag Object:  Cell set    1 (cs0001_) HeatXferCellSetOptions MEF90 Heat transfer Cell Set options
>  Flux = 0. ; [J.s^(-1).m^(-3) / J.s^(-1).m^(-2)] (f): Internal / applied heat flux
>  TemperatureBC =  FALSE; Temperature has Dirichlet boundary Condition (Y/N)
>  boundaryTemperature = 0. [K] (); Temperature boundary value
>  advectionVector = 0. 0. 0. ; [m.s^(-1)] (V): advection vector
> 
> even when -help is not passed in the command line, so that these messages are not drowned in Vec, SNES etc help messages.
> 
> Is there an easy way to achieve the same thing when using PetscOptionsXXX or PetscOptionsGetXXX?
> 
> Ideally, I’d like to be able to do <progName> -mef90_help and display only the help messages associated to the calls to PetscOptionsXXX or PetscOptionsGetXXX I made and have been executed. Does that make sense?
> 
> Regards,
> Blaise
> 
> — 
> Canada Research Chair in Mathematical and Computational Aspects of Solid Mechanics (Tier 1)
> Professor, Department of Mathematics & Statistics
> Hamilton Hall room 409A, McMaster University
> 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada 
> https://urldefense.us/v3/__https://www.math.mcmaster.ca/bourdin__;!!G_uCfscf7eWS!fgK0I4XQdmA4YFzlulAe0gnPsrtmmt_KjqXJy9r3CefbaPNCHyAQIZFpe-XT4H2K0zjYzsxw7ZuSQtzS4WfS1ZUg$  | +1 (905) 525 9140 ext. 27243
>