🤙 Dynamic dispatch through closures in C++.

Today I realized that I, since closures are equivalent to a thunk,
which can be used to simulate dynamic dispatch,
it is possible to do dynamic dispatch in C++ without subclassing,
and this is a very functional approach.

Author: rentruewang

.github/workflows/format.yaml

@@ -2,7 +2,7 @@ name: Format
 on: [push]
 jobs:
   format-cpp:
-    name: 📀 Formatting
+    name: 📀 Formatting C++
     runs-on: ubuntu-latest
     steps:
       # Global part
@@ -11,17 +11,17 @@ jobs:
 
       # C++ part
       - name: 🏗️ 🏃 clang-format
-        uses: DoozyX/clang-format-lint-action@v0.17
+        uses: DoozyX/clang-format-lint-action@v0.20
         with:
           source: ./cpp
           extensions: h,c,hpp,cpp
-          clangFormatVersion: 17
+          clangFormatVersion: 20
 
   formta-py:
     defaults:
       run:
         working-directory: ./python
-    name: 📀 Formatting
+    name: 📀 Formatting Python
     runs-on: ubuntu-latest
     steps:
       - name: 🔔 Check out

cpp/polymorphism.cpp

@@ -0,0 +1,42 @@
+/// Copyright (c) RenChu Wang - All Rights Reserved
+
+#include <functional>
+#include <iostream>
+#include <string>
+#include <vector>
+
+struct A {
+    int a;
+};
+
+struct B {
+    float b;
+};
+
+struct C {
+    std::string c;
+};
+
+int main() {
+    A a{899};
+    B b{935};
+    C c{"song"};
+
+    // Now I'm using closure to simulate a thunk,
+    // which is a fat (function) pointer + data / state,
+    // which can be used to implement dynamic dispatch (as in Go).
+    std::function<int(int)> fa{[=](int num) { return a.a + num; }};
+
+    std::function<int(int)> fb{[=](int num) { return b.b * num; }};
+
+    std::function<int(int)> fc{[&](int num) { return int(c.c.size()) - num; }};
+
+    std::vector<std::function<int(int)>> funcs{fa, fb, fc};
+
+    // Dynamic dispatching.
+    // This is very functional because this is similar to haskell's currying.
+    // Each f is essentially a thunk in STG.
+    for (auto&& f : funcs) {
+        std::cout << f(1) << "\n";
+    }
+}

python/pyproject.toml

@@ -6,7 +6,7 @@ authors = [
 ]
 license = {text = "MIT"}
 readme = "README.md"
-dynamic = ["version"]
+version = "0.0.0"
 requires-python = ">=3.13"
 
 [build-system]