Make component more functionnal

include/ftxui/component/button.hpp

@@ -1,36 +1,35 @@
 #ifndef FTXUI_COMPONENT_BUTTON_HPP
 #define FTXUI_COMPONENT_BUTTON_HPP
 
-#include <functional>
-#include <string>
+#include <functional>  // for function
+#include <string>      // for wstring
 
-#include "ftxui/component/component.hpp"
-#include "ftxui/dom/elements.hpp"
-#include "ftxui/screen/box.hpp"
+#include "ftxui/component/component.hpp"       // for Component
+#include "ftxui/component/component_base.hpp"  // for ComponentBase
+#include "ftxui/dom/elements.hpp"              // for Element
+#include "ftxui/screen/box.hpp"                // for Box
 
 namespace ftxui {
 struct Event;
 
 /// @brief A button. An action is associated to the click event.
 /// @ingroup dom
-class Button : public Component {
+class ButtonBase : public ComponentBase {
  public:
+  // Access this interface from a Component
+  static ButtonBase* From(Component);
+
   // Constructor.
-  Button() = default;
-  Button(std::wstring label) : label(label) {}
-  ~Button() override = default;
-
-  /// The Button label.
-  std::wstring label = L"button";
-
-  /// Called when the user press the "enter" button.
-  std::function<void()> on_click = [] {};
+  ButtonBase(const std::wstring* label, std::function<void()> on_click);
+  ~ButtonBase() override = default;
 
   // Component implementation.
   Element Render() override;
   bool OnEvent(Event) override;
 
  private:
+  const std::wstring* label_;
+  std::function<void()> on_click_;
   Box box_;
 };