Refactor Command#handlers

lib/command.js

@@ -10,16 +10,6 @@ const defaultVersionAction = instance => console.log(instance.meta.version);
 const lastCommandHost = new WeakMap();
 const lastAddedOption = new WeakMap();
 
-const handlers = ['init', 'applyConfig', 'finishContext', 'action'].reduce((res, name) => {
-    res.initial[name] = name === 'action' ? self : noop;
-    res.setters[name] = function(fn) {
-        this.handlers[name] = fn.bind(null);
-
-        return this;
-    };
-    return res;
-}, { initial: {}, setters: {} });
-
 export default class Command {
     constructor(usage = '') {
         const [name, params] = usage.trim().split(/(\s+.*)$/);
@@ -34,12 +24,34 @@ export default class Command {
             help: null
         };
 
-        this.handlers = { ...handlers.initial };
-        Object.assign(this, handlers.setters);
+        this.handlers = {
+            init: noop,
+            applyConfig: noop,
+            finishContext: noop,
+            action: self
+        };
 
         this.help();
     }
 
+    // handlers
+    init(fn) {
+        this.handlers.init = fn.bind(null);
+        return this;
+    }
+    applyConfig(fn) {
+        this.handlers.applyConfig = fn.bind(null);
+        return this;
+    }
+    finishContext(fn) {
+        this.handlers.finishContext = fn.bind(null);
+        return this;
+    }
+    action(fn) {
+        this.handlers.action = fn.bind(null);
+        return this;
+    }
+
     // definition chaining
     extend(fn, ...args) {
         fn(this, ...args);