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Environment Specification in the import_ Functions

Source: R/import_env.R
import_env.Rd

The env argument in the import_ functions specify where the functions, exported objects, or alias object will be placed.
The following can be specified for env:

  • NULL: If env = NULL, the objects will be placed in the caller environment.

  • an environment.

  • a string, giving the name of the search path, as given by search, to place the objects in.
    If multiple search paths have the specified name, an error is returned.

  • a number larger than 1 and smaller than length(search()), giving the position of the search path to place the objects in.

If env is a string or number, and thus points to a place in the search path, the search path evironment is not allowed to be any of the following:

  • a package path (their names start with 'package:')

  • a tools path (their names start with 'tools:')

  • the Global environment ('.GlobalEnv')

  • autoloads search path ('Autoloads')

  • a path at position 1 or length(search())

Attempting to use such a path results in an error.
The user can use the searchenv_ functions, provided by 'tinycodet', to safely add or remove custom search paths.

The default value for env is NULL.

See also

tinycodet_import

Examples


search()
#>  [1] ".GlobalEnv"        "package:magrittr"  "package:tinycodet"
#>  [4] "package:stats"     "package:graphics"  "package:grDevices"
#>  [7] "package:utils"     "package:datasets"  "package:methods"  
#> [10] "Autoloads"         "tools:callr"       "package:base"     
searchenv_add("my_ops")
search()
#>  [1] ".GlobalEnv"        "my_ops"            "package:magrittr" 
#>  [4] "package:tinycodet" "package:stats"     "package:graphics" 
#>  [7] "package:grDevices" "package:utils"     "package:datasets" 
#> [10] "package:methods"   "Autoloads"         "tools:callr"      
#> [13] "package:base"     

exports <- import_ls("stringi", c("infix", "rp"))
#> c("%s!=%", "%s!==%", "%s$%", "%s*%", "%s+%", "%s<%", "%s<=%", 
#> "%s==%", "%s===%", "%s>%", "%s>=%", "%stri!=%", "%stri!==%", 
#> "%stri$%", "%stri*%", "%stri+%", "%stri<%", "%stri<=%", "%stri==%", 
#> "%stri===%", "%stri>%", "%stri>=%", "stri_datetime_add", "stri_datetime_add<-", 
#> "stri_sub", "stri_sub<-", "stri_sub_all", "stri_sub_all<-", "stri_subset", 
#> "stri_subset<-", "stri_subset_charclass", "stri_subset_charclass<-", 
#> "stri_subset_coll", "stri_subset_coll<-", "stri_subset_fixed", 
#> "stri_subset_fixed<-", "stri_subset_regex", "stri_subset_regex<-"
#> )
import_from("stringi", exports, env = "my_ops")
#> Import & method registration complete

foo <- searchenv_get("my_ops")
all(exports %in% names(foo))
#> [1] TRUE

search()
#>  [1] ".GlobalEnv"        "my_ops"            "package:magrittr" 
#>  [4] "package:tinycodet" "package:stats"     "package:graphics" 
#>  [7] "package:grDevices" "package:utils"     "package:datasets" 
#> [10] "package:methods"   "Autoloads"         "tools:callr"      
#> [13] "package:base"     
searchenv_rm("my_ops", which(search() == "my_ops"))
search()
#>  [1] ".GlobalEnv"        "package:magrittr"  "package:tinycodet"
#>  [4] "package:stats"     "package:graphics"  "package:grDevices"
#>  [7] "package:utils"     "package:datasets"  "package:methods"  
#> [10] "Autoloads"         "tools:callr"       "package:base"