allow custom msg in ProgressCounter (solves #70)

inst/include/RcppThread/Progress.hpp

@@ -129,11 +129,12 @@ class ProgressCounter : public ProgressPrinter {
     //! constructs a progress counter.
     //! @param numIt total number of iterations.
     //! @param printEvery how regularly to print updates (in seconds).
-    ProgressCounter(size_t numIt, size_t printEvery) :
-        ProgressPrinter(numIt, printEvery)
+    ProgressCounter(size_t numIt, size_t printEvery, std::string custom_msg = "Computing: ") :
+        ProgressPrinter(numIt, printEvery), cmsg(custom_msg)
     {}
 
 private:
+    std::string cmsg;
     //! prints progress in percent to the R console (+ an estimate of remaining
     //! time).
     void printProgress() {
@@ -142,7 +143,7 @@ class ProgressCounter : public ProgressPrinter {
         if (it_ == numIt_)
             isDone_ = true;
         std::ostringstream msg;
-        msg << "\rComputing: " << progressString();
+        msg << "\r" << cmsg << progressString();
         Rcout << msg.str();
     }
 };

tests/tests.cpp

@@ -456,6 +456,18 @@ testProgressCounter()
     });
 }
 
+// [[Rcpp::export]]
+void
+testProgressCounter2()
+{
+    // 20 iterations in loop, update progress every 1 sec
+    RcppThread::ProgressCounter cntr(20, 1, "Test message: ");
+    RcppThread::parallelFor(0, 20, [&](int i) {
+        std::this_thread::sleep_for(std::chrono::milliseconds(100));
+        cntr++;
+    });
+}
+
 // [[Rcpp::export]]
 void
 testProgressBar()

tests/testthat/tests.R

@@ -90,7 +90,11 @@ if (RcppThread:::hasAtomicSupport()) {
         # ------------------------------------------------------
         context("Progress tracking")
         test_that("ProgressCounter works", {
-            expect_output(testProgressCounter(), "100% \\(done\\)")
+            expect_output(testProgressCounter(), "Computing: 100% \\(done\\)")
+        })
+
+        test_that("ProgressCounter works", {
+            expect_output(testProgressCounter2(), "Test message: 100% \\(done\\)")
         })
 
         test_that("ProgressBar works", {