use context plugin

things/koishi-plugin-init/src/index.ts

-import { Context } from "koishi-core";
-import _ from "lodash";
-
-import "source-map-support/register";
+import 'source-map-support/register';
+import { PluginContext, Plugin, Apply } from 'koishi-dev-utils';
+import _ from 'lodash';
 
 interface Config {
   prefix: string;
 }
 
-export const name = "plugin_name";
-export function apply(ctx: Context, config: Config = { prefix: "message" }) {
-  ctx.command("echo <message:text>").action((argv, message) => {
-    return _.join([config.prefix, message], ":");
-  });
+@Plugin('my-plugin')
+class MyPlugin extends PluginContext<Config> {
+  @Apply
+  init() {
+    this.command('echo <message:text>').action((argv, message) => {
+      return _.join([this.config.prefix, message], ':');
+    });
+  }
 }
+
+export = new MyPlugin();