From 6f346f3357c8759ebb5a4e980d056fda5e27abd8 Mon Sep 17 00:00:00 2001
From: "Zed A. Shaw" <zed.shaw@gmail.com>
Date: Sun, 9 Feb 2025 21:30:54 -0500
Subject: [PATCH] Two possible ways to fix drawable to avoid the const problem,
 but not quite right.

---
 meson.build                        |  6 +++++-
 sfml-const/{fixed.cpp => fix1.cpp} |  4 ++--
 sfml-const/{fixed.hpp => fix1.hpp} |  2 +-
 sfml-const/fix2.cpp                | 26 ++++++++++++++++++++++++++
 sfml-const/fix2.hpp                | 27 +++++++++++++++++++++++++++
 sfml-const/original.cpp            |  2 +-
 6 files changed, 62 insertions(+), 5 deletions(-)
 rename sfml-const/{fixed.cpp => fix1.cpp} (68%)
 rename sfml-const/{fixed.hpp => fix1.hpp} (78%)
 create mode 100644 sfml-const/fix2.cpp
 create mode 100644 sfml-const/fix2.hpp

diff --git a/meson.build b/meson.build
index ae0dfb3..813c184 100644
--- a/meson.build
+++ b/meson.build
@@ -54,6 +54,10 @@ executable('sfml-original', 'sfml-const/original.cpp',
   override_options: exe_defaults,
   dependencies: dependencies)
 
-executable('sfml-fixed1', 'sfml-const/fixed.cpp',
+executable('sfml-fix1', 'sfml-const/fix1.cpp',
+  override_options: exe_defaults,
+  dependencies: dependencies)
+
+executable('sfml-fix2', 'sfml-const/fix2.cpp',
   override_options: exe_defaults,
   dependencies: dependencies)
diff --git a/sfml-const/fixed.cpp b/sfml-const/fix1.cpp
similarity index 68%
rename from sfml-const/fixed.cpp
rename to sfml-const/fix1.cpp
index 338273a..6cfcf02 100644
--- a/sfml-const/fixed.cpp
+++ b/sfml-const/fix1.cpp
@@ -1,9 +1,9 @@
 #include <iostream>
-#include "constness.hpp"
+#include "fix1.hpp"
 
 using std::cout;
 
-void Shape::draw(RenderTarget& target) const {
+void Shape::draw(RenderTarget& target) {
   cout << "shape draw\n";
 }
 
diff --git a/sfml-const/fixed.hpp b/sfml-const/fix1.hpp
similarity index 78%
rename from sfml-const/fixed.hpp
rename to sfml-const/fix1.hpp
index 54e18c5..41ac504 100644
--- a/sfml-const/fixed.hpp
+++ b/sfml-const/fix1.hpp
@@ -12,5 +12,5 @@ class Drawable {
 
 class Shape : public Drawable {
   public:
-  void draw(RenderTarget& target) const override;
+  void draw(RenderTarget& target) override;
 };
diff --git a/sfml-const/fix2.cpp b/sfml-const/fix2.cpp
new file mode 100644
index 0000000..3faf153
--- /dev/null
+++ b/sfml-const/fix2.cpp
@@ -0,0 +1,26 @@
+#include <iostream>
+#include "fix2.hpp"
+
+using std::cout;
+
+void RenderTarget::draw(const Drawable& drawable) {
+  drawable.draw(*this);
+}
+
+void Shape::draw(RenderTarget& target) const {
+  cout << "shape draw\n";
+}
+
+void Shape::render_to(RenderTarget &target) {
+  cout << "shape render_to instead\n";
+}
+
+int main() {
+  RenderTarget target;
+  Shape shape;
+
+  target.draw(shape);
+
+  shape.render_to(target);
+  return 0;
+}
diff --git a/sfml-const/fix2.hpp b/sfml-const/fix2.hpp
new file mode 100644
index 0000000..75581d1
--- /dev/null
+++ b/sfml-const/fix2.hpp
@@ -0,0 +1,27 @@
+#pragma once
+
+class Drawable;
+
+class RenderTarget {
+  public:
+    void draw(const Drawable& drawable);
+};
+
+class Drawable {
+  public:
+    /*
+     * NOTE: This requires const because RenderTarget
+     * pass itself in as a *this which is always const.
+     * If you need to draw without const then invert it
+     * then use shape.render_to(target) instead.
+     */
+    virtual void draw(RenderTarget& target) const = 0;
+
+    virtual void render_to(RenderTarget& target) = 0;
+};
+
+class Shape : public Drawable {
+  public:
+  void draw(RenderTarget& target) const override;
+  void render_to(RenderTarget &target) override;
+};
diff --git a/sfml-const/original.cpp b/sfml-const/original.cpp
index 275ea98..618d567 100644
--- a/sfml-const/original.cpp
+++ b/sfml-const/original.cpp
@@ -1,5 +1,5 @@
 #include <iostream>
-#include "constness.hpp"
+#include "original.hpp"
 
 using std::cout;