Update the performance example

Author: iorate

README.md

@@ -196,7 +196,7 @@ performance.cpp
 #include "../flexargs.hpp"
 using namespace flexargs;
 
-int calc1(std::string_view op, int lhs = 100, int rhs = 200) {
+int calc_v0(std::string_view op, int lhs = 100, int rhs = 200) {
     if (op == "add") {
         return lhs + rhs;
     } else if (op == "sub") {
@@ -221,7 +221,7 @@ namespace keywords {
 }
 
 template <class ...Args>
-int calc2(Args &&...args) {
+int calc_v1(Args &&...args) {
     auto [op, lhs, rhs] = match(
         parameter<std::string_view>(keywords::op),
         parameter<int>(keywords::lhs) = 100,
@@ -248,17 +248,17 @@ int main() {
     using namespace keywords;
     constexpr int N = 100000000;
     {
-        std::cout << "call calc1() " << N << " times:\n";
+        std::cout << "call calc_v0() " << N << " times:\n";
         boost::timer::auto_cpu_timer timer;
         for (int i = 0; i < N; ++i) {
-            calc1("sub", 999);
+            calc_v0("sub", 999);
         }
     }
     {
-        std::cout << "call calc2() " << N << " times:\n";
+        std::cout << "call calc_v1() " << N << " times:\n";
         boost::timer::auto_cpu_timer timer;
         for (int i = 0; i < N; ++i) {
-            calc2(op = "sub", lhs = 999);
+            calc_v1(op = "sub", lhs = 999);
         }
     }
 }
@@ -267,9 +267,9 @@ int main() {
 $ g++ -std=c++17 -O2 performance.cpp -lboost_timer -o performance
 
 $ ./performance
-call calc1() 100000000 times:
+call calc_v0() 100000000 times:
  0.284747s wall, 0.296875s user + 0.000000s system = 0.296875s CPU (104.3%)
-call calc2() 100000000 times:
+call calc_v1() 100000000 times:
  0.729618s wall, 0.718750s user + 0.000000s system = 0.718750s CPU (98.5%)
 ```
 When I compiled it by GCC 8.2.0 with '-O2' flag and executed it in my environment, the extra execution time was approximately 0.45s. That means the overhead per call was 4.5ns, which is probably an acceptable value in most cases.

example/performance.cpp

@@ -16,7 +16,7 @@
 #include "../flexargs.hpp"
 using namespace flexargs;
 
-int calc1(std::string_view op, int lhs = 100, int rhs = 200) {
+int calc_v0(std::string_view op, int lhs = 100, int rhs = 200) {
     if (op == "add") {
         return lhs + rhs;
     } else if (op == "sub") {
@@ -41,7 +41,7 @@ namespace keywords {
 }
 
 template <class ...Args>
-int calc2(Args &&...args) {
+int calc_v1(Args &&...args) {
     auto [op, lhs, rhs] = match(
         parameter<std::string_view>(keywords::op),
         parameter<int>(keywords::lhs) = 100,
@@ -68,17 +68,17 @@ int main() {
     using namespace keywords;
     constexpr int N = 100000000;
     {
-        std::cout << "call calc1() " << N << " times:\n";
+        std::cout << "call calc_v0() " << N << " times:\n";
         boost::timer::auto_cpu_timer timer;
         for (int i = 0; i < N; ++i) {
-            calc1("sub", 999);
+            calc_v0("sub", 999);
         }
     }
     {
-        std::cout << "call calc2() " << N << " times:\n";
+        std::cout << "call calc_v1() " << N << " times:\n";
         boost::timer::auto_cpu_timer timer;
         for (int i = 0; i < N; ++i) {
-            calc2(op = "sub", lhs = 999);
+            calc_v1(op = "sub", lhs = 999);
         }
     }
 }
@@ -87,8 +87,8 @@ int main() {
 $ g++ -std=c++17 -O2 performance.cpp -lboost_timer -o performance
 
 $ ./performance
-call calc1() 100000000 times:
+call calc_v0() 100000000 times:
  0.284747s wall, 0.296875s user + 0.000000s system = 0.296875s CPU (104.3%)
-call calc2() 100000000 times:
+call calc_v1() 100000000 times:
  0.729618s wall, 0.718750s user + 0.000000s system = 0.718750s CPU (98.5%)
 */