Execute a function
This function constructs and evaluates a call to .fn.
It has two primary uses:
To call a function with arguments stored in a list (if the
function doesn't support dynamic dots). Splice the
list of arguments with !!!.
To call every function stored in a list (in conjunction with map()/
lapply())
exec(.fn, ..., .env = caller_env())
.fn |
A function, or function name as a string. |
... |
<dynamic> Arguments for |
.env |
Environment in which to evaluate the call. This will be
most useful if |
args <- list(x = c(1:10, 100, NA), na.rm = TRUE)
exec("mean", !!!args)
exec("mean", !!!args, trim = 0.2)
fs <- list(a = function() "a", b = function() "b")
lapply(fs, exec)
# Compare to do.call it will not automatically inline expressions
# into the evaluated call.
x <- 10
args <- exprs(x1 = x + 1, x2 = x * 2)
exec(list, !!!args)
do.call(list, args)
# exec() is not designed to generate pretty function calls. This is
# most easily seen if you call a function that captures the call:
f <- disp ~ cyl
exec("lm", f, data = mtcars)
# If you need finer control over the generated call, you'll need to
# construct it yourself. This may require creating a new environment
# with carefully constructed bindings
data_env <- env(data = mtcars)
eval(expr(lm(!!f, data)), data_env)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.