check fixes

NEWS.md

@@ -33,6 +33,8 @@ Minor changes:
   to more easily label spikes. (#203; thanks @mattansb for the suggestion).
 * The `arrow` parameter is now supported for intervals in `geom_slabinterval()`
   (#206; thanks to @ASKurz for the suggestion).
+* Optional arguments to automatically partially-applied functions can now be 
+  passed a `waiver()` to use their default value (see `auto_partial()`).
 * Several dependency reductions: removed {cowplot}, {purrr}, {forcats}, 
   {palmerpenguins}, and {modelr} from *Suggests*; moved {tidyselect} and {dplyr}
   from *Imports* to *Suggests*. The latter two are only strictly necessary for 

R/auto_partial.R

@@ -163,14 +163,12 @@ auto_partial = function(f, name = NULL, waivable = TRUE) {
   required_arg_names = required_arg_names[required_arg_names != "..."]
 
   # build an expression to apply waivers to optional args
-  if (waivable) {
+  process_waivers = if (waivable) {
     optional_args = f_args[!is_required_arg]
-    process_waivers = map2_(optional_args, names(optional_args), function(arg_expr, arg_name) {
+    map2_(optional_args, names(optional_args), function(arg_expr, arg_name) {
       arg_sym = as.symbol(arg_name)
-      expr(if (inherits(!!arg_sym, "waiver")) !!arg_sym = !!arg_expr)
+      expr(if (inherits(!!arg_sym, "waiver")) (!!arg_name) = !!arg_expr)
     })
-  } else {
-    process_waivers = list()
   }
 
   # build a logical expression testing to see if any required args are missing
@@ -189,18 +187,19 @@ auto_partial = function(f, name = NULL, waivable = TRUE) {
     partial_self
   }
 
-  if (length(required_arg_names) == 0) {
-    partial_self_if_missing_args = list()
-  } else {
-    partial_self_if_missing_args = list(expr(
+  partial_self_if_missing_args = if (length(required_arg_names) > 0) {
+    expr({
       if (!!any_required_args_missing) return((!!partial_self_f)(!!name, waivable = !!waivable))
-    ))
+    })
   }
 
   new_f = new_function(
     f_args,
     expr({
-      !!!process_waivers
+      # no idea why, but covr::package_coverage() fails if the next line doesn't
+      # have { } around it. It is not necessary for normal execution. Must have
+      # something to do with how covr adds hooks for tracing execution.
+      { !!!process_waivers }
       !!!partial_self_if_missing_args
       !!!f_body
     }),