add cxxopts example and update lua (#73)

* add cxxopts example

* use new tags for lua

* update readme

* update readme

* update lua

* typo

examples/cxxopts/CMakeLists.txt

@@ -0,0 +1,24 @@
+cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
+
+# ---- Options ----
+
+option(ENABLE_TEST_COVERAGE "Enable test coverage" OFF)
+
+# ---- Dependencies ----
+
+include(../../cmake/CPM.cmake)
+
+CPMAddPackage(
+  NAME cxxopts
+  GITHUB_REPOSITORY jarro2783/cxxopts
+  VERSION 2.2.0
+  OPTIONS
+    "CXXOPTS_BUILD_EXAMPLES Off"
+    "CXXOPTS_BUILD_TESTS Off"
+)
+
+# ---- Create binary ----
+
+add_executable(CPMExampleCXXOpts main.cpp)
+target_link_libraries(CPMExampleCXXOpts cxxopts)
+set_target_properties(CPMExampleCXXOpts PROPERTIES CXX_STANDARD 17 COMPILE_FLAGS "-Wall -pedantic -Wextra -Werror")

examples/cxxopts/main.cpp

@@ -0,0 +1,23 @@
+#include <cxxopts.hpp>
+#include <iostream>
+
+int main(int argc, char ** argv) {
+  cxxopts::Options options("MyProgram", "One line description of MyProgram");
+  options.add_options()
+    ("h,help", "Show help")
+    ("d,debug", "Enable debugging")
+    ("f,file", "File name", cxxopts::value<std::string>());
+
+  auto result = options.parse(argc, argv);
+  
+  if (result["help"].as<bool>()) {
+    std::cout << options.help() << std::endl;
+    return 0;
+  }
+
+  for (auto arg: result.arguments()) {
+    std::cout << "option: " << arg.key() << ": " << arg.value() << std::endl;
+  }
+
+  return 0;
+}