Detect print() and cat() Calls (CRAN-Unsafe)

Check whether R source files contain direct calls to print() or cat(), which are generally not permitted by CRAN policies. Output should use message instead.

These functions parse R source code into an AST and identify every SYMBOL_FUNCTION_CALL token whose text is "print" or "cat". Each match is reported with the line number, the full source line, and a caret marker pointing at the offending call.

When fix = TRUE, the function performs a simple text replacement of print( and cat( with message( on the affected lines. The replacement uses word-boundary matching to avoid false positives inside other identifiers (e.g. sprintf or print.myclass).

Usage

package_print_and_cat(path = NULL, test_included = TRUE, fix = FALSE, ...)

detect_print_and_cat(path = NULL, fix = FALSE, ...)

Arguments

path

For detect_print_and_cat(): path to an R file. If NULL and RStudio is available, the active document path is used.

For package_print_and_cat(): path to the root directory of an R package. If NULL, the function walks up from the active document to find the package root.

test_included

Logical, used only by package_print_and_cat(). If TRUE (the default), .R files under tests/testthat/ are also scanned.

fix

Logical. If TRUE, replace print(/cat( with message( directly in the source file(s). Default is FALSE.

...

Additional arguments passed to utils::methods (currently unused).

Value

Invisibly returns TRUE if no calls were found, FALSE otherwise. Side-effect messages and caret markers are emitted via cli and message.

Functions

• package_print_and_cat(): Scans all .R files in an R package (and optionally tests/testthat/), aggregated with per-file reporting.

Single file vs package scope

detect_print_and_cat()

Operates on one R file. When path is NULL and RStudio is available, the currently active document is used automatically.

package_print_and_cat()

Scans all .R files in a package's R/ directory, plus tests/testthat/ when test_included = TRUE. Results are aggregated into a single report showing per-file summaries.

Examples

# \donttest{
# --- Single file ---
tmp <- tempfile(fileext = ".R")
writeLines('print("hello")', tmp)
detect_print_and_cat(tmp)
#> print("hello")
#> ^^^^^^
#> ✖ Found 1 unsupported call on line 
#> 1.

# --- With auto-fix ---
detect_print_and_cat(tmp, fix = TRUE)
#> ✔ Fixed 1 line in file1b24c10d6d2.R.
#> print("hello")
#> ^^^^^^
#> ✖ Found 1 unsupported call on line 
#> 1.

# --- Entire package ---
pkg <- tempfile()
dir.create(file.path(pkg, "R"), recursive = TRUE)
writeLines('cat("debug\\n")', file.path(pkg, "R", "example.R"))
writeLines(c("Package: example", "Version: 0.0.1"),
           file.path(pkg, "DESCRIPTION"))
package_print_and_cat(pkg)
#> ℹ Scanning 1 file...
#> ✖ Found `print()`/`cat()` calls in 1 of 1 file:
#> example.R
#> Line 1:
#>     cat("debug\n")
#> ^^^^
#> 
# }