Warning / Error handling

[mnlevy1981]

We've talked via email about adding an error code as an optional argument (to allow modules to handle errors on their own rather than getting a stop call which is sure to cause issues with MPI). There would also be a cvmix_error module in src/ to handle the errors for the stand-alone drivers... likely just printing a statement followed by a stop call.

On the same note, we should put some thought into handling warnings - I think we should print warnings in a variety of cases (over-writing existing parameters, using cvmix_put to write a scalar into an array, etc)... but there should be an easy way to suppress the warnings. I'm leaning towards a namelist option that sets the global variable lwarn, but I'm open to other ideas - a namelist variable stored somewhere else? Copious ifdefs along with a compile-time setting? Going with the namelist option, I'm picturing a cvmix_warn routine that takes a string as an argument and prints "WARNING: " // warn_string... with the check against lwarn or whatever in the cvmix_warn routine. Maybe something like

module cvmix_warn

public :: cvmix_warn
public :: cvmix_set_lwarn

logical, private, save :: lwarn = .true.

...

end module cvmix_warn

So by default we print all warnings, but the user can call cvmix_set_lwarn(.false.) to suppress them (and then later call cvmix_set_lwarn(.true.) to turn them back on).