Cache implementation. Badge returns an anonymous prototype

.env.example

@@ -1,3 +1,4 @@
 APP_PORT=1406
 APP_URL=
+APP_CACHE=1000
 GITHUB_TOKEN=PersonalAccessToken

package.json

@@ -23,6 +23,7 @@
     "koa": "^1.2.1",
     "koa-route": "^2.4.2",
     "koa-static": "^2.0.0",
+    "memoizee": "^0.4.1",
     "octokat": "^0.4.18"
   },
   "devDependencies": {

src/Badge.js

@@ -1,23 +1,35 @@
-export default {
-  draw (src) {
-    if (this.$env.APP_URL) {
-      return this.$env.APP_URL + '/' + src
-    }
-    return '/' + src
-  },
-  show (id, repo) {
-    return this.$app.github.users(id)
-    .fetch()
-    .then(user => {
-      if (user.hireable) {
-        return 'hireable-yes.svg'
-      }
-      return 'hireable-no.svg'
-    })
-    .catch(e => {
-      return 'hireable-error.svg'
-      // console.log(e.json ? e.json.message : e.message, e.status)
-    })
-    .then(src => this.draw(src))
+import Cache from 'memoizee'
+let Badge = function (app, env) {
+  this.$app = app
+  this.$env = env
+  if (this.$env.APP_CACHE) {
+    this.show = Cache(this._show, { maxAge: this.$env.APP_CACHE, promise: true })
+  } else {
+    this.show = this._show
+  }
+}
+
+Badge.prototype.draw = function (src) {
+  if (this.$env.APP_URL) {
+    return this.$env.APP_URL + '/' + src
   }
+  return '/' + src
+}
+
+Badge.prototype._show = function (id, repo) {
+  return this.$app.github.users(id)
+  .fetch()
+  .then(user => {
+    if (user.hireable) {
+      return 'hireable-yes.svg'
+    }
+    return 'hireable-no.svg'
+  })
+  .catch(e => {
+    return 'hireable-error.svg'
+    // console.log(e.json ? e.json.message : e.message, e.status)
+  })
+  .then(src => this.draw(src))
 }
+
+export default Badge

src/index.js

@@ -16,8 +16,7 @@ app.context.github = new Octokat({
   token: process.env.GITHUB_TOKEN
 })
 
-Badge.$app = app.context
-Badge.$env = process.env
+const badge = new Badge(app.context, process.env)
 
 app.use(Serve(path.join(__dirname, '../public'), {
   maxage: 31536000000
@@ -32,7 +31,7 @@ app.use(Route.get('/p/:user', function * (user) {
 }))
 
 app.use(Route.get('/:user/:repo?', function * show (id, repo) {
-  yield Badge.show(id, repo).then(src => {
+  yield badge.show(id, repo).then(src => {
     this.redirect(src)
   })
 }))