This is test code for libpeas using vala

libpeas-test.vala

namespace PApp {
    void main () {
        print ("Hello\n");
        for (;;) {
            string? r = stdin.read_line ();
            if (r != null && r != "quit") {
                //do_something (r);
                Plugins.run_cmd (r);
            } else {
                return;
            }
        }
    }

    void do_something (string read) {
        print ("read: "+read+"\n");
    }

    private struct Command {
        string trigger;
        string plugin;
    }

    namespace Plugins {

        private Peas.Engine engine;
        private Peas.ExtensionSet exten_set;
        private SList<Command?> commands;

        internal void init () {
            engine = Peas.Engine.get_default ();
            engine.add_search_path ("./plugins", null);
            exten_set = new Peas.ExtensionSet (engine, typeof(Plugin));
            exten_set.extension_added.connect(on_extension_added);
            exten_set.extension_removed.connect(on_extension_removed);
        }

        public bool load (string name) {
            var plug_info = engine.get_plugin_info (name);
            if (plug_info == null) {
                warning ("Plugin Not found");
                return false;
            }
            return engine.try_load_plugin (plug_info);
        }
        public bool unload (string name) {
            var plug_info = engine.get_plugin_info (name);
            if (plug_info == null) {
                warning ("Plugin Not found");
                return false;
            }
            return engine.try_unload_plugin (plug_info);
        }
        internal void run_cmd (string hook) {
            foreach (var cmd in commands) {
                if (cmd.trigger ==  hook) {
                    run_plug_cb (cmd.plugin, hook);
                }
            }
        }

        public void run_plug_cb (string plug_name, string line) {
            var plugin_info = engine.get_plugin_info (plug_name);
            var exten = exten_set.get_extension (plugin_info) as Plugin;
            exten.do_something (line);
        }

        internal void register_command (string hook, string plug) {
            var cmd = Command () {
                trigger = hook,
                plugin = plug
            };
            commands.append (cmd);
        }
        private void on_extension_added(Peas.ExtensionSet extension_set, Peas.PluginInfo info, GLib.Object exten) {
            var plugin = exten as Plugin;

            try {
                plugin.init();
            } catch (Error e) {
                warning(e.message);
            }
        }

        private void on_extension_removed(Peas.ExtensionSet extension_set, Peas.PluginInfo info, GLib.Object exten) {
            commands.foreach((data) => {
                    if (data.plugin == info.get_module_name())
                        commands.remove(data);
                    });
        }
    }

    public interface Plugin : Peas.ExtensionBase {

        public abstract void init ();

        protected void register_str (string str) {
            var plugin_info = get_plugin_info();
            var plugin = plugin_info.get_module_name();

            Plugins.register_command(plugin, str);
        }

        public abstract void do_something (string str);
    }
}