bug: the default value for `coordinate_check_method` in `ModflowPrtprp` of 'eager' errors in latest MODFLOW (6.6.3)

[rubencalje]

Describe the bug
The default value for coordinate_check_method in ModflowPrtprp of 'eager' gives the following error in latest MODFLOW-(verion 6.6.3):

ERROR REPORT:

  1. Input tag "COORDINATE_CHECK_METHOD" read from file
     "from_scratch_prt.prp" is still under development. Install the nightly
     build or compile from source with IDEVELOPMODE = 1.

Therefore I think the default value in FloPy should be None.

Expected behavior
No error in latest MODFLOW

Desktop (please complete the following information):

• OS: Windows
• Version FloPy: 3.10.0, MODFLOW: 6.6.3

[wpbonelli]

Hi @rubencalje coordinate_check_method was added in MF6.7.0 which was released a few days ago. Flopy 3.10 is "paired" with MF6.7.0.

But I agree it is bad that the latest flopy breaks with MF6.6.3 and earlier, since it tries to set the default value. Will think on how to handle this, and leave this open in the meantime.

More broadly, this points to the lack of an explicit mf6/flopy version compatibility policy. Something we have at the front of our minds for flopy 4.x.

[wpbonelli]

@rubencalje

#2712 is one way to fix this, although it would mean an MF6 input file written by flopy may no longer completely capture the user's intent, as options taking the default value will be omitted unless you deliberately opt into writing them.

Another way proposed by @Manangka would be to make MF6 tolerant of unrecognized options. It could just show a warning instead of stopping with an error. I feel that might be the best way forward. Do you have any thoughts?

In the longer term, we are aiming to make flopy 4.x smarter about the MF6 binary it's driving. So it could e.g. detect when the binary doesn't match the flopy module wrapping it, and prompt you to resync.

[rubencalje]

Thank you for looking into my issue. When posting this issue I did not realize there already was a newer MODFLOW version available.

I don’t really have a preference for a solution (both can also be implemented probably). It may indeed be counterintuitive if users do not see their FloPy-input in the MODFLOW input-files. Ignoring unrecognized options by MODFLOW (and displaying a warning) seems like a good solution.

I would set the default value of an optional argument (like coordinate_check_method) in FloPy to None, so only when a user assigns a value to an argument it is added to the MODFLOW input-files. But that may not be possible in the way FloPy handles arguments maybe...

[wpbonelli]

just FYI we currently release mf6 and flopy in lockstep because flopy's mf6 module needs to match the new mf6. tho with flopy 4 the idea is to decouple so mf6 can be released without mandating a flopy release.

I agree re: defaulting optional variables to None. At least by default. That would better capture intent. It will have to wait til 4 though. I think you are right that the way 3.x handles it can't easily be changed.

Thanks for sharing your thoughts