1 files changed, 53 insertions, 0 deletions
diff --git a/lib/sol2/examples/source/functions_empty_arguments.cpp b/lib/sol2/examples/source/functions_empty_arguments.cpp
new file mode 100644
index 0000000..6d93e9b
--- /dev/null
+++ b/lib/sol2/examples/source/functions_empty_arguments.cpp
@@ -0,0 +1,53 @@
+#define SOL_ALL_SAFETIES_ON 1
+#include <sol/sol.hpp>
+
+#include "assert.hpp"
+#include <iostream>
+
+int main(int, char*[]) {
+	std::cout << "=== functions empty args ===" << std::endl;
+
+	// sol::reference, sol::Stack_reference,
+	// sol::object (and main_* types) can all be
+	// used to capture "nil", or "none" when a function
+	// leaves it off
+	auto my_defaulting_function = [](sol::object maybe_defaulted) -> int {
+		// if it's nil, it's "unused" or "inactive"
+		bool inactive = maybe_defaulted == sol::lua_nil;
+		if (inactive) {
+			return 0;
+		}
+		if (maybe_defaulted.is<int>()) {
+			int value = maybe_defaulted.as<int>();
+			return value;
+		}
+		return 1;
+	};
+
+	sol::state lua;
+	lua.open_libraries(sol::lib::base);
+
+	// copy function in (use std::ref to change this behavior)
+	lua.set_function("defaulting_function", my_defaulting_function);
+
+	sol::string_view code = R"(
+		result = defaulting_function(24)
+		result_nothing = defaulting_function()
+		result_nil = defaulting_function(nil)
+		result_string = defaulting_function('meow')
+		print('defaulting_function(24), returned:', result)
+		print('defaulting_function(), returned:', result_nothing)
+		print('defaulting_function(nil), returned:', result_nil)
+		print('defaulting_function(\'meow\'), returned:', result_string)
+		assert(result == 24)
+		assert(result_nothing == 0)
+		assert(result_nil == 0)
+		assert(result_string == 1)
+	)";
+
+	lua.safe_script(code);
+
+	std::cout << std::endl;
+
+	return 0;
+}
+\ No newline at end of file