RTXUI

Appearance

HTML/CSS Hot-Reloading ​

RTXUI can re-read a component's HTML template and <style> block from its C++ source file while the application is running, updating the live interface without recompiling.

How It Works ​

EnableHotReload() records which source file defines the component, using std::source_location, and which member variable holds its template. While the application runs, the event loop polls the file's modification time; when the file is saved, the raw string literal is re-extracted from the C++ source, re-parsed, and the component's DOM subtree is rebuilt and re-bound.

Only the template text is reloaded — the compiled C++ stays as it was. Changes to methods, bindings, event handlers, or member variables still require a rebuild.

Usage ​

Call EnableHotReload() in the component's constructor:

cpp
#include <rtxui/rtxui.hpp>

class MyPanel : public rtxui::Component<MyPanel> {
 public:
  std::string_view view = R"html(
    <div class="panel">
      <h1>Live Panel</h1>
      <p>Modify this text, save the file, and watch the terminal update.</p>
    </div>
    <style>
      .panel {
        border: heavy;
        border-color: rgb(59, 130, 246);
        padding: 1;
      }
      h1 { color: rgb(234, 179, 8); }
    </style>
  )html";

  MyPanel() {
    EnableHotReload();
  }
};

By default the template is assumed to live in a member named view. If yours is named differently, pass the name:

cpp
EnableHotReload("my_custom_view");

An overload also accepts an explicit file path, for cases where std::source_location does not point at the file you want watched:

cpp
EnableHotReload("view", "src/panels/my_panel.cpp");

Limitations ​

  • Only HTML markup and <style> blocks inside the watched raw string literal are reloaded.
  • The extractor locates the template by the member variable's name in the source text, so the declaration must keep the form std::string_view view = R"html(...)html";.
  • If the edited template fails to parse, the error is printed to stderr and the previous template stays active.
  • A <style> block failing to parse (including one whose text is built from reactive/interpolated state, not just file-watched hot reload) also prints to stderr by default. Since an RTXUI app typically owns the terminal in raw mode, that print lands mid-frame instead of a scrollback the user could read — call rtxui::SetCssErrorHandler(handler) once (e.g. in main()) to redirect these into your own UI (an app that renders arbitrary/live-edited CSS, like a playground, should do this). handler receives a rtxui::CssError{message, line, column}; pass nullptr to restore the default stderr behavior.