vc(ov) argument: allow function and rename?

[ghost]

Sorry, I placed this first as a comment to commit 03bdb72, but don not know if it gets through to you this way. So I opened this issue as suggestions:

Would it be possible to pass a vcov calculation function? This is fairly standard option, see, e.g. lmtest::coeftest.

I think, in other packages/functions the argument is called vcov or vcov., see packages lmtest, sandwich, car, ... (with the dot being there for imho historical reasons (pre NAMESPACE times) and allowing for partial argument matching). Thus, maybe renaming the vc argument could be beneficial from a consistency perspective?

[leeper]

1. Not sure about passing a function. Is passing FUN much more convenient than passing FUN(x)?
2. Probably a good idea to standardize the name. Will explore that - probably to vcov.

[ghost]

About the passing of a function:
Well, some users might just be to used to it, given that so many other packages allow for passing either the matrix itself or an estimation function for it.

Allowing for passing a function could become convienent in your own code in margins once you encounter two different models where the function can be applied on. (Not sure if that could be the case for margins in the future; think of a list of models inputted for some comparison or so).

[leeper]

I see. I guess there's no harm it making it an option. sandwich does this with a pretty simple conditional statement