make tinyplot_add compatible with do.call(tinyplot)

NEWS.md

@@ -20,6 +20,10 @@ where the formatting is also better._
 - `type_text()` now defaults to displaying `y` values if an explicit `labels`
   arg is not provided, mirroring the behaviour of the base `text()` function.
   (#501 @grantmcdermott)
+- Determining the last call of the `tinyplot()` generic in preparation for
+  `tinyplot_add()` is now more robust so that it is compatible with `do.call()`
+  again (reported by @FlorianSchwendinger). This is achieved by inspecting
+  the functions called rather than just their names. (#504 @zeileis)
 
 ### Documentation
 

R/tinyplot.R

@@ -652,10 +652,10 @@ tinyplot.default = function(
   assert_logical(add)
   if (!add) {
     calls = sys.calls()
-    tinyplot_calls = "(^tinyplot$)|(^tinyplot::tinyplot$)|(^plt$)|(^tinyplot::plt)|(^tinyplot:::)"
-    idx = grep(tinyplot_calls, sapply(calls, function(k) k[[1]]))
+    is_tinyplot_call <- function(x) identical(tinyplot, try(eval(x[[1L]]), silent = TRUE))
+    idx = which(vapply(calls, is_tinyplot_call, FALSE))
     if (length(idx) > 0) {
-      set_environment_variable(.last_call = calls[[idx[1]]])
+      set_environment_variable(.last_call = calls[[idx[1L]]])
     }
   }
 

inst/tinytest/test-tinyplot_add.R

@@ -75,6 +75,15 @@ f = function() {
 expect_snapshot_plot(f, label = "tinyplot_lollipop")
 
 
+# use tinyplot_add() after do.call(tinyplot)
+f = function() {
+  d = data.frame(x = 1:5, y = sin(1:5))
+  do.call(tinyplot, list(y ~ x, data = d))
+  do.call(tinyplot_add, list(type = "h"))
+}
+expect_snapshot_plot(f, label = "tinyplot_do_call")
+
+
 # check that we are avoiding recursive margins for facets, by properly restoring
 # the original state
 f = function() {
@@ -83,4 +92,4 @@ f = function() {
   tinyplot(Sepal.Width ~ Sepal.Length, facet = ~Species, data = iris)
   tinyplot_add(type = "lm")
 }
-expect_snapshot_plot(f, label = "tinyplot_add_no_recursive_margins")
+expect_snapshot_plot(f, label = "tinyplot_add_no_recursive_margins")