feat: 用Boost.DLL从指定目录用加载动态链接库！

plugins/command/meson.build

@@ -0,0 +1,4 @@
+command = shared_library('command', 'plugin.cpp',
+  dependencies : plugin_dep,
+  install : true,
+  install_dir : 'lib/loader')

plugins/command/plugin.cpp

@@ -0,0 +1,17 @@
+#include "plugin.hpp"
+
+#include <iostream>
+#include <string>
+
+using std::string;
+
+namespace loader {
+
+const string Command::name() const {
+    return "command";
+}
+Command::~Command() {
+    std::cout << "destructing command" << std::endl;
+}
+
+}

plugins/command/plugin.hpp

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <string>
+
+#include "interface.hpp"
+
+namespace loader {
+
+class Command : public Interface {
+public:
+    const std::string name() const;
+    ~Command();
+};
+
+extern "C" BOOST_SYMBOL_EXPORT Command plugin;
+Command plugin;
+
+}