Feature Request: Change default parameters to extract attributes of `.df`

[André Veríssimo]

Feature Idea

Currently, the default parameters of metadata, domain (and in the future verbose) are set with NULL

This implicitly means that it will default back to the data frame attributes (if they exist)

Proposal

We could change it to extract the respective attribute from .df

diff --git a/R/length.R b/R/length.R
index 05fadff..d760245 100644
--- a/R/length.R
+++ b/R/length.R
@@ -58,9 +58,9 @@
 #'
 #' adsl <- xportr_length(adsl, metadata, domain = "adsl")
 xportr_length <- function(.df,
-                          metadata = NULL,
-                          domain = NULL,
-                          verbose = NULL,
+                          metadata = attr(.df, "_xportr.df_metadata_"),
+                          domain = attr(.df, "_xportr.df_arg_"),
+                          verbose = attr(.df, "_xportr.df_verbose_") %||% getOption("xportr.length_verbose", "none"),
                           metacore = deprecated()) {
   if (!missing(metacore)) {
     lifecycle::deprecate_stop(

Benefits

• The default parameters become explicit
  • As this is the behaviour of the code, it will default to the data frame attribute if the argument is NULL
• Cleans up repetitive code in the body of the xportr_* functions

Cons

• Non-technical users might find the attr odd on the parameter documentation

Alternatives

• Use helper functions (extract_metadata(.df), extract_domain(.df), extract_verbose(.df))
  • instead of attr() function
• Keep as is

Extra

For verbose parameter we could go the extra mile and also include the fallback to the global option

Relevant Input

No response

Relevant Output

No response

Reproducible Example/Pseudo Code

No response