# Current problematic code in R 3.5.3
reformulateProb <- function (termlabels, response=NULL, intercept = TRUE)
{
	if(!is.character(termlabels) || !length(termlabels))
		stop("'termlabels' must be a character vector of length at least one")
	has.resp <- !is.null(response)
	termtext <- paste(if(has.resp) "response", "~",
					  paste(termlabels, collapse = "+"),
					  collapse = "")
	if(!intercept) termtext <- paste(termtext, "- 1")
	rval <- eval(parse(text = termtext, keep.source = FALSE)[[1L]])
	if(has.resp) rval[[2L]] <-
		if(is.character(response)) as.symbol(response) else response
	## response can be a symbol or call as  Surv(ftime, case)
	environment(rval) <- parent.frame()
	rval
}

# My simple solution
reformulateMySol <- function (termlabels, response=NULL, intercept = TRUE) {
	if(!is.character(termlabels) || !length(termlabels))
		stop("'termlabels' must be a character vector of length at least one")
	has.resp <- !is.null(response)
	
	termtext <- paste(if(has.resp) "response", if(has.resp) "~",
					  paste(paste0("`", termlabels, "`"), collapse = "+"),
					  collapse = "")
	if(!intercept) termtext <- paste(termtext, "- 1")
	rval <- eval(parse(text = termtext, keep.source = FALSE)[[1L]])
	if(has.resp) rval[[2L]] <-
		if(is.character(response)) as.symbol(response) else response
	## response can be a symbol or call as  Surv(ftime, case)
	environment(rval) <- parent.frame()
	rval
}

# Current development with str2lang, which I don't have and didn't/couldn't test
reformulateRDevel <- function (termlabels, response=NULL, intercept = TRUE, env = parent.frame())
{
	## an extension of formula.character()
	if(!is.character(termlabels) || !length(termlabels))
		stop("'termlabels' must be a character vector of length at least one")
	termtext <- paste(termlabels, collapse = "+")
	if(!intercept) termtext <- paste(termtext, "- 1")
	terms <- str2lang(termtext)
	fexpr <-
		if(is.null(response))
			call("~", terms)
	else
		call("~",
			 ## response can be a symbol or call as  Surv(ftime, case)
			 if(is.character(response))
			 	tryCatch(str2lang(response),
			 			 error = function(e) {
			 			 	sc <- sys.calls()
			 			 	sc1 <- lapply(sc, `[[`, 1L)
			 			 	isF <- function(cl) is.symbol(cl) && cl == quote(reformulate)
			 			 	reformCall <- sc[[match(TRUE, vapply(sc1, isF, NA))]]
			 			 	warning(warningCondition(message = paste(sprintf(
			 			 		"Unparseable 'response' \"%s\"; use is deprecated.  Use as.name(.) or `..`!",
			 			 		response),
			 			 		conditionMessage(e), sep="\n"),
			 			 		class = c("reformulate", "deprecatedWarning"),
			 			 		call = reformCall)) # , domain=NA
			 			 	as.symbol(response)
			 			 })
			 else response,
			 terms)
	formula(fexpr, env)
}

# Test control
reformulateProb(termlabels = c("Var1", "Var2"), response = "Resp")
# Test problem
reformulateProb(termlabels = c("Va r1", "Var2"), response = "Resp")


# Test control
reformulateMySol(termlabels = c("Var1", "Var2"), response = "Resp")
# Test problem
reformulateMySol(termlabels = c("Va r1", "Var2"), response = "Resp")


# Test control
reformulateRDevel(termlabels = c("Var1", "Var2"), response = "Resp")
# Test problem
reformulateRDevel(termlabels = c("Va r1", "Var2"), response = "Resp")