Re: [Libmesh-users] Very Basic: Makefile for Modifying and Creating New Examples (new to libmesh)

[Jed B. <je...@je...>]

Roy Stogner <roy...@ic...> writes:

> On Tue, 7 Nov 2017, Jed Brown wrote:
>
>> If you have a list of options that you handle, you can use
>> PetscOptionsHasName(NULL, NULL, "-your-option", NULL) so that PETSc
>> knows it is used and won't warn about it.  Might be simpler than munging
>> the command line before passing it off.
>
> Much simpler, thanks!  I didn't know that method existed.
>
>>> Do PETSc options ever include an =?
>>
>> No.
>
> That's two out of three categories down... except if I understand your
> third response, it's a necessary category for us to bother with?

Unfortunately.

>>> We could have a method which strips out any argument with an = in
>>> it...
>>>
>>> Oh, but we'd *also* need to handle application-specific
>>> position-independent arguments which *aren't* just input file
>>> overrides, like the options we grab via GetPot in
>>> src/apps/calculator.C
>>
>> PETSc doesn't process or complain about these.
>
> And that's the third.

I think I misinterpreted what you were referring to here.

> But I don't yet understand: why not?  Is it just because we use
> double-dashes and the PETSc unused-option detection looks for
> single-dashes?

How about a slightly different solution.  Before calling PetscFinalize,
call PetscOptionsLeftGet and loop over the options, calling
PetscOptionsHasName if you would have recognized it.  So if it contains
an = or leading --, you could ignore it.