allow debug / debugonce("<S4>")

git-svn-id: https://svn.r-project.org/R/trunk@87345 00db46b3-68df-0310-9c12-caf00c1e9a41

Author: maechler

doc/NEWS.Rd

@@ -361,6 +361,10 @@
 
       \item \code{axisTicks(usr, ...)} documentation clarification for
       \code{log=TRUE}, fixing bug \PR{18821} thanks to Duncan Murdoch.
+
+      \item \code{debug()} and \code{debugonce(fun)} now also accept a
+      string \code{fun} when it names an S4 generic, fixing \PR{18822}
+      thanks to Michael Jagan.
     }
   }
 }

src/library/base/man/debug.Rd

@@ -18,7 +18,8 @@ isdebugged(fun, signature = NULL)
 debuggingState(on = NULL)
 }
 \arguments{
-  \item{fun}{any interpreted \R function.}
+  \item{fun}{any interpreted \R function or a character string naming
+    one.}
   \item{text}{a text string that can be retrieved when the browser is entered.}
   \item{condition}{a condition that can be retrieved when the browser is
     entered.}

src/library/methods/R/debug.R

@@ -2,11 +2,8 @@
                          once = FALSE)
 {
     stopifnot(is.null(condition), identical(text, ""))
-    if (is.primitive(fun))
-        fun <- getGeneric(fun)
-    if(!is(fun, "genericFunction"))
-        stop("Function must be an S4 generic")
-    
+    fun <- getGeneric(fun, mustWork = TRUE)
+
     if(isdebugged(fun, signature = signature))
         return(invisible(NULL))