quoting.env: Given a list of names, build an environment such that...
In crowding/vadr: Macros, metaprogramming, and pleasant programming idioms.

Description Usage Arguments Details Value Note Author(s) Examples

Technically, this defines two nested environments, the outer containing functions and the inner containing names, and returns the inner.

1	quoting.env(names, parent = emptyenv(), call.names = names)

`names`	The names the environment should define.
`parent`	The parent environment (defaults to the empty environment)
`call.names`	The functions the enclosing environment should define. Decaults to `names`, but sometimes you want these to be different.

This somewhat esoteric function mostly intended to be used by expand_macros

The environment constructed.

This will cause errors when the expression has missing arguments. The expression might be preprocessed (somewhow?) to take missing arguments out.

Peter Meilstrup

en <- quoting.env(c('+', '(', 'a', 'b', '*'), environment())

evalq(a+b, en) # a+b
evalq(a+(b*a), en) # a+(b*a)
z <- 100
evalq(a+(b*a)*z, en) #a+(b*a)*100

##We can build a function that does something like substitute() like this:
ersatz.substitute <- function(expr, envir=arg_env(expr)) {
  parent <- as.environment(envir)
  en <- quoting.env(setdiff(all.names(expr), ls(parent)), parent)
  eval(expr, en)
}

ersatz.substitute(quote(a+b+c), list(b=quote(q+y))) # returns a+(q+y)+c