Constructing functions from symbols using 'bquote' (or alternatives to doing so)

Let's say I have an object of type "symbol" representing the name of a function. For example:

nm <- quote(mean)

I want to construct a function f whose body uses the function named by the symbol nm. For example:

f <- function(x, do = c("something", "nothing")) {
  switch(match.arg(do), something = mean(x), nothing = x)
}

I want to construct this function identically, which implies that I would not be satisfied with the following approach:

factory <- function(name) {
  func <- match.fun(name)
  function(x, do = c("something", "nothing")) {
    switch(match.arg(do), something = func(x), nothing = x)
  }
}
g <- factory(nm)

since the body of g is not body(f) and the environment of g is not environment(f).

One approach that I've considered is bquote:

h <- eval(bquote({
  function(x, do = c("something", "nothing")) {
    switch(match.arg(do), something = .(nm)(x), nothing = x)
  }
}))

bquote gets me most of the way there, but one issue is that the print output of h doesn't contain the substituted value of nm by default:

h
## function(x, do = c("something", "nothing")) {
##     switch(match.arg(do), something = .(nm)(x), nothing = x)
##   }

print(h, useSource = FALSE)
## function (x, do = c("something", "nothing")) 
## {
##     switch(match.arg(do), something = mean(x), nothing = x)
## }

The cause seems to be the srcref attribute of h:

identical(f, h)
## [1] TRUE
identical(f, h, ignore.srcref = FALSE)
## [1] FALSE

My question is: How might one approach the general problem of constructing f from nm?

My conditions on the constructed function h are that identical(f, h) should be TRUE and that the output of print(h) should contain the substituted value of nm, similar to print(f).

I would welcome answers improving on my existing bquote approach, or answers suggesting a new approach, or answers explaining why what I want to do is not actually possible...

Solution

Reading through ?srcref, it seems that there are two idiomatic ways to improve the bquote approach. The first uses removeSource to recursively clean a function that preserves its source code:

h <- removeSource(eval(bquote({
  function(x, do = c("something", "nothing")) {
    switch(match.arg(do), something = .(nm)(x), nothing = x)
  }
})))
h

function (x, do = c("something", "nothing")) 
{
    switch(match.arg(do), something = mean(x), nothing = x)
}

The second avoids preserving the source code altogether:

op <- options(keep.source = FALSE)
h <- eval(bquote({
  function(x, do = c("something", "nothing")) {
    switch(match.arg(do), something = .(nm)(x), nothing = x)
  }
}))
options(op)
h

function (x, do = c("something", "nothing")) 
{
    switch(match.arg(do), something = mean(x), nothing = x)
}

Actually, ?options states that the default value of keep.source is interactive(), so both approaches are somewhat redundant in non-interactive contexts.