Some updates

Author: mcjazzyfunky

package.json

@@ -1,6 +1,6 @@
 {
   "name": "js-messages",
-  "version": "0.1.15",
+  "version": "0.1.16",
   "license": "LGPL-3.0",
   "homepage": "https://github.com/js-works/js-messages",
   "main": "index.js",

src/main/api/defineMessage.ts

@@ -0,0 +1,9 @@
+import buildMessageCreator from '../internal/buildMessageCreator'
+import MessageInitializer from '../internal/types/MessageInitializer'
+import MessageCreator from '../internal/types/MessageCreator'
+
+export default function defineMessage<K extends String, A extends any[]>
+  (type: K, initializer: MessageInitializer<A> = null): MessageCreator<K, A, any, any> {
+
+  return buildMessageCreator(type, initializer)
+}

src/main/api/defineMessages.ts

@@ -1,19 +1,11 @@
 import Signature from '../internal/types/Signature'
 import MessagesConfig from '../internal/types/MessagesConfig'
 import MessageInitializer from '../internal/types/MessageInitializer'
+import MessageCreator from '../internal/types/MessageCreator'
+import buildMessageCreator from '../internal/buildMessageCreator';
 
 type Func<A extends any[], R> = (...args: A) => R
 
-type MessageCreator<K, A extends any[], P, M> = {
-  readonly type: K,
-  
-  (...args: A): {
-    type: K,
-    payload?: P,
-    meta?: M
-  }
-}
-
 type Arguments<A extends any[], I extends MessageInitializer<any>>
   = I extends Func<A, any>
     ? Signature<I>
@@ -45,38 +37,7 @@ function defineMessages<T extends MessagesConfig>(config: T):
   for (let i = 0; i < keys.length; ++i) {
     const key = keys[i]
 
-    if (typeof config[key] === 'function') {
-      const getPayload = config[key] as Function
-    
-      ret[key] = function (/* arguments */) {
-        const payload = getPayload.apply(null, arguments)
-
-        return { type: key, payload }
-      }
-    } else {
-      const
-        messageConfig = config[key] as { payload?: Function, meta?: Function },
-        getPayload = messageConfig.payload,
-        getMeta = messageConfig.meta
-
-      ret[key] = function (/* arguments */) {
-        const msg: any = { type: key }
-
-        if (getPayload) {
-          msg.payload = getPayload.apply(null, arguments)
-        }
-
-        if (getMeta) {
-          msg.meta = getMeta.apply(null, arguments)
-        }
-
-        return msg
-      }
-    }
-
-    Object.defineProperty(ret[key], 'type', {
-      value: key
-    })
+    ret[key] = buildMessageCreator(key, config[key])
   }
 
   return ret

src/main/internal/buildMessageCreator.ts

@@ -0,0 +1,44 @@
+import MessageInitializer from './types/MessageInitializer'
+import MessageCreator from './types/MessageCreator'
+
+export default function buildMessageCreator<K extends String, A extends any[]>
+  (type: K, initializer: MessageInitializer<A> = null): MessageCreator<K, A, any, any> {
+  
+  let ret: any
+
+  if (!initializer) {
+   const msg = Object.freeze({ type })
+
+    ret = () => msg
+  } else if (typeof initializer === 'function') {
+    const getPayload = initializer as Function
+    
+    ret = function (/* arguments */) {
+      const payload = getPayload.apply(null, arguments)
+
+      return { type, payload }
+    }
+  } else {
+    const { payload: getPayload, meta: getMeta } = initializer as { payload?: Function, meta?: Function }
+
+    ret = function (/* arguments */) {
+      const msg: any = { type: type }
+
+      if (getPayload) {
+        msg.payload = getPayload.apply(null, arguments)
+      }
+
+      if (getMeta) {
+        msg.meta = getMeta.apply(null, arguments)
+      }
+
+      return msg
+    }
+  }
+
+  Object.defineProperty(ret, 'type', {
+    value: type
+  })
+
+  return ret
+}

src/main/internal/types/MessageCreator.ts

@@ -0,0 +1,11 @@
+type MessageCreator<K, A extends any[], P, M> = {
+  readonly type: K,
+  
+  (...args: A): {
+    type: K,
+    payload?: P,
+    meta?: M
+  }
+}
+
+export default MessageCreator

src/main/js-messages.ts

@@ -1,5 +1,7 @@
+import defineMessage from './api/defineMessage'
 import defineMessages from './api/defineMessages'
 
 export {
+  defineMessage,
   defineMessages
 }

src/test/api/defineMessage.test.ts

@@ -0,0 +1,41 @@
+import { describe, it } from 'mocha'
+import { expect } from 'chai'
+
+import defineMessage from '../../main/api/defineMessage'
+
+const
+  action1 = defineMessage('ACTION1'),
+  action2 = defineMessage('ACTION2', (value: number = 0) => value),
+  action3 = defineMessage('ACTION3', (value: number = 21) => ({ value })),
+  
+  action4 = defineMessage('ACTION4', {
+    payload: (value: number = 42) => ({ value }),
+    meta: (value: number = 42) => ({ half: value / 2})
+  })
+
+describe('defineMessage', () => {
+  it('should create messages with neigther payload nor meta', () => {
+    expect(action1())
+      .to.eql({ type: 'ACTION1' })
+  })
+
+  it('should create messages properly with payload getter', () => {
+    expect(action2())
+      .to.eql({ type: 'ACTION2', payload: 0 })
+
+    expect(action2(2))
+      .to.eql({ type: 'ACTION2', payload: 2 })
+   
+    expect(action3())
+      .to.eql({ type: 'ACTION3', payload: { value: 21 } })
+
+    expect(action3(2))
+      .to.eql({ type: 'ACTION3', payload: { value: 2 } })
+   
+    expect(action4())
+      .to.eql({ type: 'ACTION4', payload: { value: 42 }, meta: { half: 21 } })
+
+    expect(action4(2))
+      .to.eql({ type: 'ACTION4', payload: { value: 2 }, meta: { half: 1 } })
+  })
+})