[R] Reassign functions called by other functions in package graphics

[John Kolassa]

I am trying to get a function written in R that calls a cascade of functions from the graphics package, and I want to eventually call replacements to functions in the graphics package instead of the originals.  Specifically, I have a function that calls qqnorm in stats, which calls qqnorm.default in stats, which calls plot in graphics, which calls plot.default and plot.new, and I want my own functions plot.default and plot.new that I entered at the command line (which I guess means that it is in .GlobalEnv).  I'd like my plot.default and plot.new called (this afternoon, at least) in place of every invocation of plot.default and plot.new resp..  So far I've tried:

reassignInPackage from R.utils: reassignInPackage("plot.default","graphics",my.plot.default) gives "Error in assignInNamespaceT(name, value, ns = pkgName, envir = env) :   locked binding of ‘plot.default’ cannot be changed", even after
unlockBinding("plot.default",as.environment("package:graphics"))

assignInNamespace seems to almost work.  Here's what I enter:

plot.default<-function(...){cat("Entered plot.default")}
plot.new<-function(...){cat("Entered plot.new")}
assignInNamespace("plot.default",plot.default,ns="graphics")
assignInNamespace("plot.new",plot.new,ns="graphics")
qqnorm(1:10)

and here's what I get:

Entered plot.newError in plot.xy(xy, type, ...) : plot.new has not been called yet

It seems as though my new plot.new is being called, but the existing plot.default is being called, even though the new version is in graphics::plot.default.  I conjecture that this is because the original plot.default got exported when the package loaded, but is there a
 way to overwrite this?  Thanks, John