feature request: documenting default argument values

[IndrajeetPatil]

Is there any possibility that roxygen2 can automatically add the default values for function arguments in the .Rd files?

For example,let's see this is the function:

foo <- function(x, d = 1) {
return(x + d)
}

In this case, I usually write something like-

#' @param x A numeric.
#' @param d A constant numeric value to add to `x` (Default : `1`).

But typically there are scores of such arguments with set default values and manually doing it means-

• this will be highly time-consuming
• this will be highly error-prone since I can change the default value (d = 2) and forget to update the documentation

If roxygen2 can automatically add the default values at the end of the param description text, that would be really neat.

[gaborcsardi]

Well, the defaults are already in the manual, in the Usage section. I agree that it can be nice to have them in the Arguments section as well, but I am not sure how easy that would be to implement. Probably not too bad.

this will be highly error-prone since I can change the default value (d = 2) and forget to update the documentation

Yes, R CMD check will catch discrepancies in the Usage section, though.

[hadley]

To me, repeating in the argument section is not terribly useful, and will require a decent amount of work because we'd need some package wide option to control the behaviour and give the user control over the precise appearance.

[IndrajeetPatil]

FWIW, {plumber} annotations do this.

For example, annotations for the following function signature:

are rendered in the docs like so: