Extract arguments from a call

Source: R/call.R

Extract arguments from a call

call_args(call)

call_args_names(call)

Arguments

call

Can be a call or a quosure that wraps a call.

Value

A named list of arguments.

Life cycle

In rlang 0.2.0, lang_args() and lang_args_names() were deprecated and renamed to call_args() and call_args_names(). See lifecycle section in call2() for more about this change.

See also

fn_fmls() and fn_fmls_names()

Examples

call <- quote(f(a, b))

# Subsetting a call returns the arguments converted to a language
# object:
call[-1]
#> a(b)

# On the other hand, call_args() returns a regular list that is
# often easier to work with:
str(call_args(call))
#> List of 2
#>  $ : symbol a
#>  $ : symbol b

# When the arguments are unnamed, a vector of empty strings is
# supplied (rather than NULL):
call_args_names(call)
#> [1] "" ""