New cpp11::messages with opt-in fmt formatting

NEWS.md

@@ -5,6 +5,7 @@
 * Error messages now output original file name rather than the temporary file name (@sbearrows, #194)
 * Fixed bug when running `cpp_source()` on the same file more than once (@sbearrows, #202)
 * Removed internal instances of `cpp11::stop()` and replaced with C++ exceptions (@sbearrows, #203)
+* Added `cpp11::messages()` feature with {fmt} library formatting for non-error messages (@sbearrows, #208)
 * Names of named lists are now resized along with the list elements (@sbearrows, #206)
 * Added optionally formatting to `stop()` and `warning()` using {fmt} library (@sbearrows, #169)
 

cpp11test/R/cpp11.R

@@ -16,6 +16,10 @@ my_warning <- function(mystring, myarg) {
   invisible(.Call(`_cpp11test_my_warning`, mystring, myarg))
 }
 
+my_message <- function(mystring, myarg) {
+  invisible(.Call(`_cpp11test_my_message`, mystring, myarg))
+}
+
 my_stop_n1fmt <- function(mystring) {
   invisible(.Call(`_cpp11test_my_stop_n1fmt`, mystring))
 }
@@ -32,6 +36,10 @@ my_warning_n2fmt <- function(mystring, myarg) {
   invisible(.Call(`_cpp11test_my_warning_n2fmt`, mystring, myarg))
 }
 
+my_message_nfmt <- function(mystring, myarg) {
+  invisible(.Call(`_cpp11test_my_message_nfmt`, mystring, myarg))
+}
+
 remove_altrep <- function(x) {
   .Call(`_cpp11test_remove_altrep`, x)
 }

cpp11test/src/cpp11.cpp

@@ -36,6 +36,14 @@ extern "C" SEXP _cpp11test_my_warning(SEXP mystring, SEXP myarg) {
     return R_NilValue;
   END_CPP11
 }
+// errors_fmt.cpp
+void my_message(std::string mystring, std::string myarg);
+extern "C" SEXP _cpp11test_my_message(SEXP mystring, SEXP myarg) {
+  BEGIN_CPP11
+    my_message(cpp11::as_cpp<cpp11::decay_t<std::string>>(mystring), cpp11::as_cpp<cpp11::decay_t<std::string>>(myarg));
+    return R_NilValue;
+  END_CPP11
+}
 // errors.cpp
 void my_stop_n1fmt(std::string mystring);
 extern "C" SEXP _cpp11test_my_stop_n1fmt(SEXP mystring) {
@@ -68,6 +76,14 @@ extern "C" SEXP _cpp11test_my_warning_n2fmt(SEXP mystring, SEXP myarg) {
     return R_NilValue;
   END_CPP11
 }
+// errors.cpp
+void my_message_nfmt(std::string mystring, std::string myarg);
+extern "C" SEXP _cpp11test_my_message_nfmt(SEXP mystring, SEXP myarg) {
+  BEGIN_CPP11
+    my_message_nfmt(cpp11::as_cpp<cpp11::decay_t<std::string>>(mystring), cpp11::as_cpp<cpp11::decay_t<std::string>>(myarg));
+    return R_NilValue;
+  END_CPP11
+}
 // find-intervals.cpp
 SEXP remove_altrep(SEXP x);
 extern "C" SEXP _cpp11test_remove_altrep(SEXP x) {
@@ -386,6 +402,8 @@ static const R_CallMethodDef CallEntries[] = {
     {"_cpp11test_gibbs_rcpp",               (DL_FUNC) &_cpp11test_gibbs_rcpp,               2},
     {"_cpp11test_gibbs_rcpp2",              (DL_FUNC) &_cpp11test_gibbs_rcpp2,              2},
     {"_cpp11test_grow_",                    (DL_FUNC) &_cpp11test_grow_,                    1},
+    {"_cpp11test_my_message",               (DL_FUNC) &_cpp11test_my_message,               2},
+    {"_cpp11test_my_message_nfmt",          (DL_FUNC) &_cpp11test_my_message_nfmt,          2},
     {"_cpp11test_my_stop",                  (DL_FUNC) &_cpp11test_my_stop,                  2},
     {"_cpp11test_my_stop_n1fmt",            (DL_FUNC) &_cpp11test_my_stop_n1fmt,            1},
     {"_cpp11test_my_stop_n2fmt",            (DL_FUNC) &_cpp11test_my_stop_n2fmt,            2},

cpp11test/src/errors.cpp

@@ -1,3 +1,4 @@
+#include "cpp11/function.hpp"
 #include "cpp11/protect.hpp"
 using namespace cpp11;
 
@@ -11,3 +12,6 @@ using namespace cpp11;
 [[cpp11::register]] void my_warning_n2fmt(std::string mystring, std::string myarg) {
   cpp11::warning(mystring, myarg.c_str());
 }
+[[cpp11::register]] void my_message_nfmt(std::string mystring, std::string myarg) {
+  cpp11::message(mystring, myarg.c_str());
+}

cpp11test/src/errors_fmt.cpp

@@ -1,4 +1,5 @@
 #define CPP11_USE_FMT
+#include "cpp11/function.hpp"
 #include "cpp11/protect.hpp"
 using namespace cpp11;
 
@@ -8,3 +9,6 @@ using namespace cpp11;
 [[cpp11::register]] void my_warning(std::string mystring, std::string myarg) {
   cpp11::warning(mystring, myarg);
 }
+[[cpp11::register]] void my_message(std::string mystring, std::string myarg) {
+  cpp11::message(mystring, myarg);
+}

cpp11test/tests/testthat/test_formatted_errors.R

@@ -13,6 +13,13 @@ test_that("cpp11::warning formatting works", {
   test2 <- c("failed", "passed")
   expect_warning(my_warning("You {}", test2[2]), "You passed", fixed = TRUE)
 })
+test_that("cpp11::message formatting works", {
+  test1 <- "message"
+  expect_message(my_message("This is a {}", test1), "This is a message", fixed = TRUE)
+
+  test2 <- c("great", "super")
+  expect_message(my_message("You're {}", test2[2]), "You're super", fixed = TRUE)
+})
 test_that("cpp11::stop works without including the fmt library", {
   test1 <- "error"
   expect_error(my_stop_n1fmt("This is a stop"), "This is a stop", fixed = TRUE)
@@ -23,3 +30,10 @@ test_that("cpp11::warning works without including the fmt library", {
   expect_warning(my_warning_n1fmt("This is a warning"), "This is a warning", fixed = TRUE)
   expect_warning(my_warning_n2fmt("This is a %s", test1), "This is a warning", fixed = TRUE)
 })
+test_that("cpp11::message works without including the fmt library", {
+  test1 <- "message"
+  expect_message(my_message_nfmt("This is a %s", test1), "This is a message", fixed = TRUE)
+
+  test2 <- c("great", "super")
+  expect_message(my_message_nfmt("You're %s", test2[2]), "You're super", fixed = TRUE)
+})

inst/include/cpp11/function.hpp

@@ -2,6 +2,7 @@
 
 #include <string.h>  // for strcmp
 
+#include <stdio.h>  // for snprintf
 #include <string>   // for string, basic_string
 #include <utility>  // for forward
 
@@ -73,4 +74,39 @@ class package {
 
   SEXP data_;
 };
+
+static auto R_message = cpp11::package("base")["message"];
+
+#ifdef CPP11_USE_FMT
+template <typename... Args>
+void message(const char* fmt_arg, Args... args) {
+  std::string msg = fmt::format(fmt_arg, args...);
+  R_message(msg.c_str());
+}
+
+template <typename... Args>
+void message(const std::string& fmt_arg, Args... args) {
+  std::string msg = fmt::format(fmt_arg, args...);
+  R_message(msg.c_str());
+}
+#else
+template <typename... Args>
+void message(const char* fmt_arg, Args... args) {
+  char buff[1024];
+  int msg = std::snprintf(buff, 1024, fmt_arg, args...);
+  if (msg >= 0 && msg < 1024) {
+    R_message(buff);
+  }
+}
+
+template <typename... Args>
+void message(const std::string& fmt_arg, Args... args) {
+  char buff[1024];
+  int msg = std::snprintf(buff, 1024, fmt_arg.c_str(), args...);
+  if (msg >= 0 && msg < 1024) {
+    R_message(buff);
+  }
+}
+#endif
+
 }  // namespace cpp11

tests/testthat/cpp11.cpp

@@ -0,0 +1,9 @@
+#include "cpp11/declarations.hpp"
+using namespace cpp11;
+// single_27.cpp
+int foo();
+extern "C" SEXP _single_27_foo() {
+  BEGIN_CPP11
+  return cpp11::as_sexp(foo());
+  END_CPP11
+}