migration.R
In box: Write Reusable, Composable and Modular R Code

## ----eval = FALSE-------------------------------------------------------------
#  library(modules)
#  
#  # …
#  
#  modname = import('prefix/modname')
#  pkgname = import_package('pkgname')

## ----eval = FALSE-------------------------------------------------------------
#  box::use(prefix/modname)
#  box::use(pkgname)

## ----eval = FALSE-------------------------------------------------------------
#  box::use(./modname)

## ----eval = FALSE-------------------------------------------------------------
#  box::use(mod_alias = prefix/modname)

## ----eval = FALSE-------------------------------------------------------------
#  box::use(
#      prefix/mod1,
#      mod = prefix/mod2,
#      pkg
#  )

## ----eval = FALSE-------------------------------------------------------------
#  # ‘modules’:
#  import('prefix/mod', attach = c('name1', 'name2'))
#  
#  # ‘box’:
#  box::use(prefix/mod[name1, name2])

## ----eval = FALSE-------------------------------------------------------------
#  # ‘modules’:
#  import('prefix/mod', attach = TRUE)
#  
#  # ‘box’:
#  box::use(prefix/mod[...])

## ----eval = FALSE-------------------------------------------------------------
#  # ‘modules’:
#  mod = import('prefix/mod', attach = c('name1', 'name2'))
#  
#  # ‘box’:
#  box::use(mod = prefix/mod[name1, name2])

## ----eval = FALSE-------------------------------------------------------------
#  # Declare alias for one name, attach other name unchanged:
#  box::use(prefix/mod[name_alias = name1, name2])
#  
#  # Declare alias for two names, attach all other exported names unchanged:
#  box::use(prefix/mod[name_alias1 = name1, name_alias2 = name2, ...])

## ----eval = FALSE-------------------------------------------------------------
#  # This function is not exported:
#  f1 = function () {}
#  
#  # This nested module is not exported
#  box::use(./nested1)
#  
#  # This function is exported:
#  #' @export
#  f2 = function () {}
#  
#  # This nested module is exported
#  #' @export
#  box::use(./nested2)

## ----eval = FALSE-------------------------------------------------------------
#  #' @export
#  box::use(
#      pkg_alias = pkg,
#      prefix/mod,
#      prefix/mod2[a, b, c]
#  )

## ----eval = FALSE-------------------------------------------------------------
#  box::export()

## ----eval = FALSE-------------------------------------------------------------
#  box::use(r/core[...])