tweak show(<non-syntactic S4generic>), fixing PR#18786 (thanks to Mic…

…hael Chirico)

git-svn-id: https://svn.r-project.org/R/trunk@87048 00db46b3-68df-0310-9c12-caf00c1e9a41

src/library/methods/R/show.R

@@ -107,8 +107,8 @@ show <- function(object) showDefault(object)
                   pkg <- object@package
                   exported <- pkg == ".GlobalEnv" || isBaseNamespace(ns <- asNamespace(pkg)) ||
                       nam %in% names(.getNamespaceInfo(ns, "exports"))
-                  showGen <- if(exported) nam # was dQuote(nam, NULL)
-                             else paste(pkg, nam, sep=":::")
+                  qnam <- deparse1(as.name(nam), backtick = TRUE) # was dQuote(nam, NULL)
+                  showGen <- if(exported) qnam else paste(pkg, qnam, sep=":::")
                   cat("Methods may be defined for arguments: ",
                       paste0(object@signature, collapse=", "), "\n",
                       "Use  showMethods(", showGen,

tests/reg-S4.R

@@ -888,3 +888,7 @@ setClass("foo")
 sealClass("foo") # failed in R < 4.5.0
 stopifnot(isSealedClass("foo"))
 stopifnot(removeClass("foo"))
+
+
+## show(<non-syntactic name>) should recommend backticks for showMethods()
+stopifnot(any(grepl("showMethods(`body<-`)", capture.output(show(`body<-`)), fixed=TRUE)))

tests/reg-S4.Rout.save

@@ -1187,3 +1187,7 @@ class(from) <- "foo"
 > stopifnot(isSealedClass("foo"))
 > stopifnot(removeClass("foo"))
 > 
+> 
+> ## show(<non-syntactic name>) should recommend backticks for showMethods()
+> stopifnot(any(grepl("showMethods(`body<-`)", capture.output(show(`body<-`)), fixed=TRUE)))
+>