metaprogramming - In R, how to turn character to verbatim expression?

Question

If I do this:

parse(text="foo()")

I get:

expression(foo())

But what I really need is:

foo()

So basically "foo()" -> foo()

Also, if I try:

as.symbol("foo()")

I get:

`foo()`

I don't want the tick marks

question from:https://stackoverflow.com/questions/65640767/in-r-how-to-turn-character-to-verbatim-expression

Answer 1

Something like this?

foo <- function(x) pi*x
eval(as.symbol("foo"))(1:10)
#[1]  3.141593  6.283185  9.424778 12.566371 15.707963 18.849556 21.991149
#[8] 25.132741 28.274334 31.415927

The return value of eval(.) can be assigned to an object and it will be a function.

f <- eval(as.symbol("foo"))
f
#function(x) pi*x

f(2)
#[1] 6.283185