isGeneric(fdef=*) fix + documentation

git-svn-id: https://svn.r-project.org/R/trunk@87383 00db46b3-68df-0310-9c12-caf00c1e9a41

Author: maechler

doc/NEWS.Rd

@@ -392,6 +392,9 @@
       integer value.  Newly, values outside the range -9 .. 9999 are warned
       about and set to a respective boundary or to the default \code{0},
       e.g., in case of an \code{NA}.
+
+      \item \code{isGeneric(fdef = print)} now works, fixing \PR{18369} thanks to
+      \I{Mikael Jagan}.
     }
   }
 }

src/library/methods/R/Methods.R

@@ -273,11 +273,10 @@ isGeneric <-
     if(is.null(fdef))
       return(FALSE)
     ## check primitives. These are never found as explicit generic functions.
-    if(isBaseFun(fdef)) {
-        if(is.character(f) && f %in% "as.double") f <- "as.numeric"
+    if(is.primitive(fdef)) {
         ## the definition of isGeneric() for a base function is that methods are defined
         ## (other than the default primitive)
-        gen <- genericForBasic(f, mustFind = FALSE)
+        gen <- genericForBasic(.primname(fdef), mustFind = FALSE)
         return(is.function(gen) && length(names(.getMethodsTable(gen))) > 1L)
     }
     if(!is(fdef, "genericFunction"))

src/library/methods/man/GenericFunctions.Rd

@@ -42,7 +42,13 @@ getGenerics(where, searchForm = FALSE)
 \section{Summary of Functions}{
   \describe{
     \item{\code{isGeneric}:}{
-      Is there a function named \code{f}, and if so, is it a generic?
+      If \code{fdef} is \code{NULL}, then test if there is a formal
+      generic function named \code{f} in the current search path or in
+      the position specified by \code{where}.
+
+      If \code{fdef} is non-\code{NULL}, then test if it is a formal
+      generic function, with name matching \code{f} if \code{f} is not
+      missing.
 
       The \code{getName} argument allows a function to find the name
       from a function definition.  If it is \code{TRUE} then the name of
@@ -51,14 +57,12 @@ getGenerics(where, searchForm = FALSE)
 
       The behavior of \code{isGeneric} and \code{\link{getGeneric}} for
       primitive functions is slightly different.  These functions don't
-      exist as formal function objects (for efficiency and historical
-      reasons), regardless of whether methods have been defined for
-      them.  A call to \code{isGeneric} tells you whether methods have
-      been defined for this primitive function, anywhere in the current
-      search list, or in the specified position \code{where}.  In
-      contrast, a call to \code{\link{getGeneric}} will return what the
-      generic for that function would be, even if no methods have been
-      currently defined for it.
+      exist as formal generic function objects (for efficiency and
+      historical reasons), regardless of whether methods have been
+      defined for them.  For a primitive function, \code{isGeneric}
+      tests whether non-default methods have been defined, whereas
+      \code{\link{getGeneric}} returns what the formal generic function
+      object would be, even if no methods have been defined.
     }
 
     \item{\code{removeGeneric}, \code{removeMethods}:}{

tests/reg-tests-1e.R

@@ -1601,7 +1601,7 @@ stopifnot(exprs = {
 
 ## options(scipen = <invalid>)
 scipenO <- getOption("scipen")
-assertErrV(options(scipen = NULL))# would work (but ..) in R <= 4.2.2
+assertErrV(options(scipen = NULL))# would work (but ..) in R <= 4.4.2
 assertErrV(options(scipen = 1:2)) # would just work
 assertErrV(options(scipen = 1e99))# would "work" w/ 2 warnings and invalid setting
 stopifnot(identical(getOption("scipen"), scipenO))# unchanged
@@ -1612,6 +1612,11 @@ stopifnot(identical(getOption("scipen"), 9999L))
 ## setting to NULL  would invalidate as.character(Sys.time())
 
 
+## PR#18369 (patch by Mikael Jagan)
+stopifnot(!isGeneric(fdef = print), !isGeneric(fdef = c), isGeneric(fdef = show))
+## gave Error  argument "f" is missing ... in R <= 4.4.2
+
+
 
 ## keep at end
 rbind(last =  proc.time() - .pt,