Promise state rewrite

R/domains.R

@@ -108,30 +108,35 @@ wrap_callback_reenter <- function(callback, domain) {
   force(callback)
   force(domain)
 
-  wrapper <- function(...) {
-    # replace = TRUE because we don't care what the current domain is; we're
-    # (temporarily) putting the world back to the way it was when the callback
-    # was bound to a promise.
-    reenter_promise_domain(domain, callback(...), replace = TRUE)
+  # We can't simply take `...` as arguments and call `callback(...)`. There are
+  # parts of this package that will inspect formals() to see if there's a
+  # `.visible` parameter in the callback. Using `match.call()` here ensures that
+  # the callback is called with the same arguments as it would have been if it
+  # were called directly.
+  #
+  # IMPORTANT NOTE: This technique changes callback arguments from lazy eval to
+  # eager eval--make sure you're OK with that before using!
+  wrapper <- function() {
+    # Evaluate the arguments in the caller's environment
+    call <- match.call()
+    # The `[-1]` is to drop the function name from the call--we just want the
+    # arguments
+    args <- lapply(call[-1], eval, parent.frame())
+    # Create and evaluate the callback call in our environment, wrapped in reenter_promise_domain
+    reenter_promise_domain(
+      domain,
+      rlang::exec(callback, !!!args),
+      # replace = TRUE because we don't care what the current domain is; we're
+      # (temporarily) putting the world back to the way it was when the callback
+      # was bound to a promise.
+      replace = TRUE
+    )
   }
+  # Copy the formals from the original callback to the wrapper, so that the
+  # wrapper can be called with the same arguments as the original callback.
+  formals(wrapper) <- formals(callback)
 
-  # There are parts of this package that will inspect formals() to see if
-  # there's a `.visible` parameter in the callback. So it's important to have
-  # the returned wrapper have the same formals as the original callback.
-  wrap_with_signature(wrapper, formals(callback))
-}
-
-wrap_with_signature <- function(func, formal_args) {
-  # func must have a `...` signature
-  stopifnot("..." %in% names(formals(func)))
-
-  args <- names(formal_args)
-  recall <- rlang::call2(
-    func,
-    !!!rlang::set_names(lapply(args, as.symbol), args)
-  )
-
-  rlang::new_function(formal_args, recall)
+  wrapper
 }
 
 globals <- new.env(parent = emptyenv())