set/fetch posterior summarization arguments from options()

[wpetry]

This feature request would enable the user to set options point function, interval type, and interval width arguments for the posterior summary functions like point_interval() and stat_pointinterval().

Currently, each posterior summarization function has defaults that the user can change, but this must be done each time the function is called. However, I typically want to re-use the same summary options for all of the posterior summaries and plots I produce within a single script. I think a good solution would be to set defaults in the options() and retrieve these each time a posterior summary function is called. Users could override these defaults by supplying arguments locally to the function or globally by changing their values in options().

One potential barrier is that the options are specified differently and have different defaults depending on the function. For example, point_interval() defaults to a median with 95% quantile interval (given as 3 separate arguments), whereas stat_pointinterval() defaults to a median with 66% and 95% quantile intervals (given as 2 arguments, point_interval and .width).

[mjskay]

I'm always a little wary of global options having a substantive affect on output, and this can also invite some amount of feature creep (what function parameters need this versus don't need this?), so I'd want to think carefully about whether and how to do this.

I wonder if there is any best practice advice around R options in packages or I ggplot extensions?

[mjskay]

Raising this in the extension developers forum to see if folks have thoughts: ggplot2-extenders/ggplot-extension-club#121