Improve C++ example -- MOS_MIGRATED_REVID=87514947

diff --git a/base_workspace/examples/cpp/README.md b/base_workspace/examples/cpp/README.md
new file mode 100644
index 0000000..fba7143
--- /dev/null
+++ b/base_workspace/examples/cpp/README.md

@@ -0,0 +1,4 @@
+C++ Examples
+============
+
+These examples demonstrate building C++ binaries, libraries, and tests.

diff --git a/base_workspace/examples/cpp/hello-fail.cc b/base_workspace/examples/cpp/hello-fail.cc
index 9b0b94a..5b561cb 100644
--- a/base_workspace/examples/cpp/hello-fail.cc
+++ b/base_workspace/examples/cpp/hello-fail.cc

@@ -1,11 +1,22 @@
 #include "examples/cpp/hello-lib.h"
 
+#include <string>
+
+using hello::HelloLib;
+using std::string;
+
+/**
+ * This is a fake test that prints "Hello barf" and then exits with exit code 1.
+ * If run as a test (cc_test), the non-0 exit code indicates to Bazel that the
+ * "test" has failed.
+ */
 int main(int argc, char** argv) {
-  const char* obj = "barf";
+  HelloLib lib;
+  string thing = "barf";
   if (argc > 1) {
-    obj = argv[1];
+    thing = argv[1];
   }
 
-  greet(obj);
+  lib.greet(thing);
   return 1;
 }

diff --git a/base_workspace/examples/cpp/hello-lib.cc b/base_workspace/examples/cpp/hello-lib.cc
index aee43ba..8e40921 100644
--- a/base_workspace/examples/cpp/hello-lib.cc
+++ b/base_workspace/examples/cpp/hello-lib.cc

@@ -1,5 +1,21 @@
 #include "examples/cpp/hello-lib.h"
 
-#include <stdio.h>
+#include <iostream>
 
-void greet(const char* obj) { printf("hello %s\n", obj); }
+using std::cout;
+using std::endl;
+using std::string;
+
+namespace hello {
+
+HelloLib::HelloLib() : HelloLib("Hello") {
+}
+
+HelloLib::HelloLib(const string& greeting) : greeting_(new string(greeting)) {
+}
+
+void HelloLib::greet(const string& thing) {
+  cout << *greeting_ << " " << thing << endl;
+}
+
+}  // namespace hello

diff --git a/base_workspace/examples/cpp/hello-lib.h b/base_workspace/examples/cpp/hello-lib.h
index 3e74c2b..555d177 100644
--- a/base_workspace/examples/cpp/hello-lib.h
+++ b/base_workspace/examples/cpp/hello-lib.h

@@ -1,6 +1,23 @@
-#ifndef EXAMPLE_WORKSPACE_CPP_HELLO_LIB_H_
-#define EXAMPLE_WORKSPACE_CPP_HELLO_LIB_H_
+#ifndef EXAMPLES_CPP_HELLO_LIB_H_
+#define EXAMPLES_CPP_HELLO_LIB_H_
 
-void greet(const char* object);
+#include <string>
+#include <memory>
 
-#endif  // EXAMPLE_WORKSPACE_CPP_HELLO_LIB_H_
+namespace hello {
+
+class HelloLib {
+ public:
+  HelloLib();
+
+  explicit HelloLib(const std::string &greeting);
+
+  void greet(const std::string &thing);
+
+ private:
+  std::unique_ptr<const std::string> greeting_;
+};
+
+}  // namespace hello
+
+#endif  // EXAMPLES_CPP_HELLO_LIB_H_

diff --git a/base_workspace/examples/cpp/hello-world.cc b/base_workspace/examples/cpp/hello-world.cc
index 305b17f..be435c3 100644
--- a/base_workspace/examples/cpp/hello-world.cc
+++ b/base_workspace/examples/cpp/hello-world.cc

@@ -1,11 +1,26 @@
 #include "examples/cpp/hello-lib.h"
 
-int main(int argc, char** argv) {
-  const char* obj = "world";
-  if (argc > 1) {
-    obj = argv[1];
-  }
+#include <string>
 
-  greet(obj);
+using hello::HelloLib;
+using std::string;
+
+/**
+ * This prints "Hello world". If it is run with arguments, it will use the first
+ * argument instead of "world". Build and run //examples/cpp:hello-world to see
+ * this program in action.
+ *
+ * This file does double-duty as a "test." It is a cc_binary, so it can also be
+ * compiled as a cc_test and Bazel will decide on whether it passed or failed
+ * based on exit code (which is always 0 here, so the test "passes"). See
+ * hello-fail.cc for an example of making a test fail.
+ */
+int main(int argc, char** argv) {
+  HelloLib lib("Hello");
+  string thing = "world";
+  if (argc > 1) {
+    thing = argv[1];
+  }
+  lib.greet(thing);
   return 0;
 }