upgrade to include mergeConfig() and getDynamicConfig()

index.js

@@ -3,7 +3,8 @@ const path = require('path')
 const commander = require('commander')
 const deepmerge = require('deepmerge')
 
-module.exports = function (rawConfig) {
+module.exports = {
+  mergeConfig: function(rawConfig) {
     if (!global.EnviConfig) {
       global.EnviConfig = rawConfig
       // 不知为何，必须定义成全局变量，才能保证多次require只执行一次。
@@ -63,4 +64,15 @@ module.exports = function (rawConfig) {
     console.log('- Final Configuration: ', global.EnviConfig)
     console.log('######## Completed System Configuration ########')
     return global.EnviConfig
+  },
+
+  getDynamicConfig: function (dynamicConfigFile='ConfigDynamic.js') { // dynamicConfigFile should be absolute or relative to the node process's dir.
+    const fullpath = path.join(process.cwd(), dynamicConfigFile)
+    if (fs.existsSync(fullpath)) {
+      delete require.cache[require.resolve(fullpath)] // delete require.cache[fullpath] 不起作用
+      return require(fullpath)
+    } else {
+      return {}
+    }
+  },
 }