Inject functions into the environment of evaluate()

Create functions in the environment specified in the envir argument of evaluate(). This can be helpful if you want to substitute certain functions when evaluating the code. To make sure it does not wipe out existing functions in the environment, only functions that do not exist in the environment are injected.

Usage

inject_funs(...)

Arguments

...

Named arguments of functions. If empty, previously injected functions will be emptied.

Value

Invisibly returns previous values.

Note

For expert use only. Do not use it unless you clearly understand it.

Examples

library(evaluate)
# normally you cannot capture the output of system
evaluate("system('R --version')")
#> <evaluation>
#> Source code: 
#>   system('R --version')

# replace the system() function
old <- inject_funs(system = function(...) {
  cat(base::system(..., intern = TRUE), sep = "\n")
})

evaluate("system('R --version')")
#> <evaluation>
#> Source code: 
#>   system('R --version')
#> Text output: 
#>   R version 4.4.1 (2024-06-14) -- "Race for Your Life"
#>   Copyright (C) 2024 The R Foundation for Statistical Computing
#>   Platform: x86_64-pc-linux-gnu
#>   
#>   R is free software and comes with ABSOLUTELY NO WARRANTY.
#>   You are welcome to redistribute it under the terms of the
#>   GNU General Public License versions 2 or 3.
#>   For more information about these matters see
#>   https://www.gnu.org/licenses/.
#>   

# restore previously injected functions
inject_funs(old)