Should there be a helper function for print methods

[EmilHvitfeldt]

All the print methods follow this pattern

parsnip/R/boost_tree.R

Lines 86 to 95 in af46f57

	print.boost_tree <- function(x, ...) {
	cat("Boosted Tree Model Specification (", x$mode, ")\n\n", sep = "")
	model_printer(x, ...)
	if (!is.null(x$method$fit$args)) {
	cat("Model fit template:\n")
	print(show_call(x))
	}
	invisible(x)
	}

What about we create a wrapper so we can do

print_helper <- function(name, x, ...) {
  cat(name, " Specification (", x$mode, ")\n\n", sep = "")
  model_printer(x, ...)
  
  if (!is.null(x$method$fit$args)) {
    cat("Model fit template:\n")
    print(show_call(x))
  }
  invisible(x)
}

print.decision_tree <- function(x, ...) {
  print_helper("Decision Tree Model", x, ...)
}

[juliasilge]

This would make it way easier to start using cli eventually, for example.

[EmilHvitfeldt]

The null model print is substantially different and should be put back in line with the rest

parsnip/R/nullmodel.R

Lines 79 to 95 in 27d5b6b

	print.nullmodel <- function(x, ...) {
	cat("Null",
	ifelse(is.null(x$levels), "Classification", "Regression"),
	"Model\n")
	x$call
	if (length(x$value) == 1) {
	cat("Predicted Value:",
	ifelse(is.null(x$levels), format(x$value), x$value),
	"\n")
	} else {
	cat("Predicted Value:\n",
	names(x$value), "\n",
	x$value,
	"\n")
	}
	}

And in its current state, the print method doesn't print that it is a null model

library(parsnip)
null_model()
#> Model Specification (classification)

[simonpcouch]

Ah, wasn't automatically closed with #739—doing so now. :)

[github-actions]

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