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Add, Remove, or Access Search Path Environments

Source: R/searchenv.R
searchenv.Rd

Functions for safely attaching, removing, or accessing environments from search path.

searchenv_add() adds a new, empty environment to the search path.
searchenv_rm() removes a user-defined environment from the search path.
searchenv_get() returns a user-defined environment from the search path.

Usage

searchenv_add(name, pos = 2L)

searchenv_rm(name, pos)

searchenv_get(name, pos)

Arguments

name

a single string giving the name for the environment in the search path.

pos

a single positive integer giving the position for the environment in the search path.

Details

These functions were designed with safety in mind.
They do not allow adding, removing, or accessing search environments like 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 add a new search path environment whose name already exists gives an error.
Attempting to remove or access a search path environmeent whose name does not exists gives an error.

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"