Rename the parameters of a function

Takes a function and a name mapping, and returns a new function where both the formals and all symbol references in the body have been renamed according to the mapping. This is typically used after from_example_to_function() to replace generated names like param_1, param_2 with meaningful names.

Usage

rename_function_params(f, mapping)

Arguments

f

A function whose parameters should be renamed.

mapping

A named character vector. Names are the current parameter names, values are the new names. Example: c(param_1 = "input_path", param_2 = "output_path").

Value

A function with renamed formals and body.

Details

Validation

The function checks that:

• All names in mapping actually exist as formals of f

• New names are unique (no duplicates)

• New names do not collide with parameters not being renamed

Limitation

If the body contains a nested function definition whose formals shadow a parameter being renamed, the shadowed references in that inner body will still be renamed. This is unlikely in practice (parameters from from_example_to_function() are named param_N) but is noted here for completeness.

Examples

fn <- function(param_1 = "in.csv", param_2 = "out.csv") {
  df <- read.csv(param_1)
  write.csv(df, param_2)
}

fn2 <- rename_function_params(fn, c(
  param_1 = "input_path",
  param_2 = "output_path"
))

# Formals were renamed:
formals(fn2)
#> $input_path
#> [1] "in.csv"
#> 
#> $output_path
#> [1] "out.csv"
#> 

# And the body too — references to `param_1` and `param_2` are
# updated in place, the function source is not edited.
body(fn2)
#> {
#>     df <- read.csv(input_path)
#>     write.csv(df, output_path)
#> }