stacking multiple calls of library(…, include.only=…) doesn’t work

Question

As of R 3.6 it’s possible to choose functions when loading a package with library(…, include.only=…).

But sometimes I’d need other functions on the fly, and stacking multiples library(…, include.only=…) doesn’t work:

> library(stringr, include.only = 'str_length')
> str_length('a')
[1] 1
> library(stringr, include.only = 'str_sub')
> str_sub('a')
Error in str_sub("a") : could not find function "str_sub"
> str_length('a')
[1] 1

so far the workaround is to unload package then reload

> devtools::unload('stringr')
> library(stringr, include.only = c('str_length', 'str_sub'))

is there another way to load functions on demand without reloading package?

Answer 1

One option would be to assign individual functions into the global environment:

str_length <- stringr::str_length
str_length('a')
# 1

str_sub <- stringr::str_sub
str_sub('a')
# "a"

str_length('a')
# 1

Or you could use box:

box::use(stringr[str_length])

str_length('a')
# 1

box::use(stringr[str_sub])
str_sub('a')
# "a"

str_length('a')
# 1